breaking news. hello, everyone. alongside anderson cooper in tel aviv, we'll get to him in a moment. let's begin with this latest information, fighting in gaza continues following yesterday's terror attack. we're seeing pictures from earlier in the day. in gaza explosions have lit up the darkness there. we're also learning hamas is holding as many as 30 people captive in gaza. residents in more than 20 israeli communities are being told to evacuate the hot spot of fighting continues to flair up. video showing israeli border police rescuing civilians after an exchange of gunfire with hamas fighters on saturday. and officials say at least 600 israelis were killed in yesterday's terror attack. and this disturbing video shows dozens of body bags stocked stacked at the site of a musical festival where hamas fighters attacked concert-goers. u.s. secretary of state antony blinken says the u.s. is trying to confirm reports that americans are among those killed. israel is striking back at targets in gaza. there you can see a mosque that was destroyed by israeli air strikes, more than 300 palestinians have been killed and 1,900 wounded in the fighting. cnn's anderson cooper is with me now from tel aviv. >> reporter: a fast moving situation on the ground, 39 or so hours since this surprise attack, this brutal attack began. clarissa ward is along the gaza border and nic robertson is in israel, too, places where are used to incoming rockets but have never seen anything like this, the ground incursions that both of those communities have experienced. clarissa, i want to start off with you. we have seen just sickening videos of women, young men, elderly people being taken, kidnapped, taken, dragged across the border brutally into gaza where they will be held hostage and used to suit the purposes of islamic jihad and hamas. there was a music festival that we've heard about that was going on. a lot of people had gathered, a lot of young people, and that is where we've seen some of the hostages were taken from. talk about what you've learned about what happened there. >> reporter: so anderson, we actually went to the site of this music festival today. i think we're only just starting now to get a sense of just how many people were killed and just how bloody and horrific this entire scenario was. the israeli government took an unprecedented step and put up a photograph on twitter that shows dozens and dozens of body bags inside a tent. these are all bodies that were taken from the scene of the festival, festival-goers who are now being identified so that their loved ones can be allowed to know what has happened to them. we went to the scene today. it is still very, very tense, a huge amount of israeli military in the area. and you see as you approach it just scores of vehicles abandoned on the roadside, shot up completely. we saw the bodies -- sorry, i should have warned the audience of the graphic pictures, of hamas fighters still lying there. there are quite a few of them. you can imagine the chaos, the fear, the terror this group of some 500 young revellers had gathered to celebrate the end of the high holidays to dance the night away, about 6:00 in the morning a barrage of rockets begin followed by the infiltration of scores of hamas militants who went through murdering and grabbing and kidnapping and taking hostages. at one point we could see actually where an israeli police vehicle had literally t-boned a truck holding hamas militants to try to stop them from carrying out this horrendous mission. and there are still so many people, andersons are and we've been in touch with some of them and families of some of them who are still looking for their loved ones, some of whom went down when they heard what was happening early in the morning. one man who went down to find his daughter is now missing. for these families, the excruciating pain of not knowing where your child or where your loved one is, whether they're alive, whether they're being held in gaza, whether they are possibly dead but this was -- this festival took place over quite a large area and people were running in so many different directions that it's difficult to get a grip on exactly how extensive the casualties were. and, as i mentioned before, as we pushed further in, the israeli military saw us and they turned us right around and they were in very alert posture with their weapons and they said you simply cannot be here, anderson. >> and nic robertson, you've been traveling along the gaza border now for an hour. you talked to a spokesperson for the idf. there are still points along the border -- that's just a helicopter passing over. there are still points that are in contention, is that right? there are still points where hamas fighters are trying to come across. >> reporter: absolutely correct. there were seven earlier in the afternoon. the idf is quite prompt in announcing when they're taking control of an area. they were announcing when they took control of the police station last night and early hours of this morning after heavy firefight. those areas in contention a couple of hours ago still appear in contention. similar experience to what clarissa is experiencing. when you come across groups of soldiers, they will be on high alert, checkpoints of soldiers, who will have the safety on their weapon because that's the posture they need to be in because they are concerned that the next person that comes up to them could be from hamas because those infiltrations are still existing. we haven't heard about any new infiltrations this evening but we were yesterday evening, we were early this morning. we heard about one this afternoon as well. we heard a burst of gunfire close of us. that was again suspected infiltration. that's what the israeli forces were up against around here. i think what we're witnessing this field medical post that earlier on when we were talking just a couple of hours ago, anderson, there were ambulances swarming around here, it was buzzing with medics and doctors. one of the ambulances have taken off, they've dispersed around the area, moving into places where the army feels they will be better ready to be used. i think the understanding we will have is they will be close to those areas of contention. they're not just helping civilians here, they're helping injured soldiers as well. it is all about trying to take back control and making sure any woul wounded, casualties, can get speedy help, anderson. >> reporter: clarissa ward, the mobilization of security forces, do they have all their troops where they want them at this stage or is it still large movements of troops and trying to get people rallied and armed and moving forward? >> reporter: we're still seeing huge amounts of movement and people arriving on the scene, some carrying duffle bags with them, large amounts of military tanks being brought into the area. we also, as nic had described, had to turn around at one stage because there was an active firefight going on with the israeli military and what we presume were hamas militants. nic said they continue to lurk or hide in plain sight in these areas. for now the focus is very much to try to route out any militants who may have infiltrated but also to build up a huge presence along that border and to try to repair the damage to the border. one of the things that i hadn't necessarily expected to see was huge flatbed trucks carrying building materials to try to repair the damage at some of these places where the border was transgressed. i'm just warning you now, anderson, because i have just lost communications on my phone here so i will not be able to hear you for a minute. >> we'll come back to you. nick, in terms of where we're at, for people in sderot, is that secured? >> ostensibly, yes. the power is off in a lot of parts in the town and it's dark so a lot of people there will have that uneasy feeling about the explosions. and some of the explosions we were hearing and the gunfire was very close. and that seemed to indicate that -- and certainly the troops on patrol, weapons ready, looking for suspected hamas militants on the streets there late this afternoon indicate that there is that potential. it's so difficult. in a way it's proving a negative. how do you know when you have them all rounded up? it's very hard to know. one can pop up and start shooting just because the area's been quiet for a few hours doesn't mean it's fully secure. it's when the fence is resecured, it's when you've got the troops in place and traps it's going to take realistically several days to know for sure that all the militants have been rounded up. it's just a very big logistical task and at night here, you can hide out pretty easily and that's despite the high-tech equipment the israeli forces have. but reestablishing the border is obviously critical. if you don't have it sealed and you don't have eyes on it, again, reestablish that level of control, you don't -- you're still open to infiltration, anderson. >> yeah, it's one of the difficulties for israeli forces is just prioritizing all the things that need to be done. i mean, sealing the multiple border places that were overrun, searching for any, you know, militant fight who are still may be hiding on the ground or actually engage in fights, dealing with the fate, just trying to figure out how many hostages have been taken, who they are, getting contacts with their loved ones, trying to figure out identifying the dead, responding to stop more rockets from being fired from gaza to all points across israel including here in tel aviv and it's been very quiet here thankfully for the last several hours and trying to knock out and track down leadership of hamas and others. the amount the israeli forces have to contend with this is overwhelming in the first two days of this. >> reporter: i think absolutely. and, again, in that environment you don't tell the enemy what you're going to do. you do want to inform the israeli population about how you're going to secure them, but you're not going to announce publicly we're moving x number of forces and x equipment down to gaza because you may need to put some of that in reserve close to jerusalem and in the west bank where violence could be triggered there. that will be an israeli military concern as well as the north, the border with lebanon. we saw sort of a testing of that, if you will, overnight. it's not clear what the other players in this multiple threat matrix, be is syria, as you were discussing earlier, be it hezbollah and other actors in the west bank, not just hamas, islamic jihad. isis is believed to have a foothold in some of the areas in the west bank. there are multiple actors, multiple threats and if you announce you're going to secure the border of gaza with a big force, you potentially leave yourself veneraulnerable and signaling you're going to be vulnerable. is it's very complex. >> we're going to take a short break. our breaking news coverage continues in a moment. a very fast-moving situation still on the ground here. we have been talking to our correspondents and people of israel. i want to bring in the head of the group -- head of diplomacy in the women's zionist association. thank you for joining me. people are reaching out to you desperate for information. what are you hearing from them? >> thank you, anderson. it's just sheer desperation and utter devastation. we don't know if their loved ones are in gaza, if they are dead and they are appealing to me for immediate channels through whatever connections i have here with government channels if we've heard anything, and it's just such a feeling of helplessness to not be able to give them an answer. and i can barely articulate the desperation coming from parents who just want to know that their children are still alive and that there is a chance for them. you know, i don't want anybody to have to deal with the phone calls from desperate parents and just hear the utter despair in their voices and desperation as they wait for word of their loved ones. this situation is very, very personal for my organization as well. >> rolene, at this point, this is 39 hours since these attacks began. there is still a lot families don't know. they don't know if their loved one has died, has been killed, murdered or if their loved one has been kidnapped. are there people in the government reaching out to them or is it so early there's still not a lot of information and that's why they're reaching out to you, they're just desperate? >> i think the situation given the nature of the depraved attacks that we've been very careful or the government is being very careful not to jeopardize any security for those who are being held captive, but there has been an appeal for family think their children might be amongst the dead to please come to central with dna samples. it's similar to what we're heard on 9/11 and the pleading is distraught and devastation. the women's international zionist organization, this is so personal. we have four day care centers in the town, we have a facility that helps with ptsd. we have been reaching out to our workers frantically to make sure that they're all okay and they're all accounted for. and also it's a community we know so well. this is a communicate we helped evacuate in 2014, just shortly after they gave us a tremendous lunch to say thank you. we now know that at least 15 of those are dead, including family. they have a project called the wall of peace where all they want is peace with their neighbors, where you can place a tile on the wall between gaza and israel. this is -- there are no words, just sorrow to explain what people are dealing with what the situation on the ground is. >> you know the situation here obviously better than most. do you ever expect there could be an attack like this? obviously rockets are a fact of life, sadly, but an attack like this in sderot and elsewhere? >> rockets we're used to which is why we have four rocket-proof day care centers. we have children in a completely rocket-proof day care center. but this is a level of depravity you only see in a horror movie. i don't think in our worst nightmare we could anticipate a situation where thousands of terrorists infiltrate our borders, our community and execute people and kidnap people and take them to probably an untold situation, an unfathomable situation in gaza. >> and, you no, we were talking to our correspondent clarissa ward who went to the site of the dance party that was taking place near the border and, again, those stories are just starting to come out about the slaughter that took place there. it's, again, more will be learned in the coming hours but it's hard to imagine the pain that the families are going through right now as they wait and they wonder where their loved one is. >> we cannot understand it. we cannot understand it unless you are a family member. just a short while ago the family members gave a press conference and i don't think that there's anybody in this country who watched that that hasn't had their heart reached out to the sheer terror coming from the parents and the absolute heartbreak in their voices. these are people that went to a rave, a party in the desert to celebrate peace, to call for peace, to think of a day where we will manifest peace between us and our neighbors. our war is not with the people of gaza. we know that they are held hostage just as much we are by terror entities. and this is why young israelis are having events on the border to call for peace. this is what they want. and this is the situation a short while ago, daca, the organization responsible for handing the remains of the dead after terror attacks and disaster have confirmed 250 bodies have been recovered there. it's the absolute unfathomable for anybody, for any family member. and citizens kept in gaza now are the elderly, are small children who must be terrified out of their mind, pregnant women, men and women who went out yesterday with nothing planned for the day except to celebrate, support, maybe just spend the day with their family and now we are living a nightmare. >> i appreciate your time tonight. thank you very much. much more ahead. we'll be right back. cnn is learning a u.s. carrier strike group is headed to the eastern mediterranean scene as israeli prepares for a large scale campaign to respond to the terror attacks we have been seeing here over the last 39 or so hours. i want to go to orrin lieberman. what are you hearing? >> this is the "u.s.s. gerald r. ford" operating and is now heading to the waters off of israel. its goal is to offer a message of support and deterrence. it was president joe biden who said yesterday that other parties, references, even if not naming hezbollah and lebanon and other groups in syria, warning them not to get involved here and that now is what the u.s. is showing with this carrier strike group that also consists of a guided missile cruiser and destroyers. the general underscored that in a statement saying u.s. centcom stands with others against the risk of expanding the conflict. in the middle east areas like qatar and other areas, those will be augmented, according to austin. you'll see f-35s, f-16s, a-10s b bolstered there. some were sent as a response against syria aggression and the purpose was to deter that sort of behavior. now what we're seeing from hamas that gets part of its funding and guidance from iran, that message expanding with the augmentation and bolstering of the fighter squadrons in the region. >> secretary antony blinken said they were working overtime to try to verify reports of dead and missing americans. any new information about that? >> reporter: we haven't gotten an official statement. we have seen the reports, the rumors circulating and we've talked to family and friends trying to find their own loved ones and their own friends. again, there's been no official statement. it is worth pointing out many. american citizens in israel are dual citizens so they are american israelis. having been there six years, i don't know the number off the top of my head. but this is partially just speculation, well over 100,000 citizens or dual american-israeli citizens in the country who have moved there and take part and live in israeli society. we have seen statements from, for example, mexico and brazil saying they believe some of their citizens were taken hostage. the only reason i point that out is this isn't simply an issue for america and israel to deal with. there are other countries trying to figure out where their own citizens are and whether they were killed or taken hostage. >> thank you. we'll talk to you in the coming hours. i understand you learned some information about the dance place and the place on the border there. >> reporter: it's reported that 260 bodies have now been discovered and recovered from the scene of the music festival. this was essentially a rave in the wilderness. videos we're seeing from just before the attack took place makes it look like your typical music festival, rave, all-night party with participants dancing. militants directly attacked people at this music festival. we have seen videos of people trying to escape and several civilians were captured and taken hostage by hamas, including that video we've seen so often of that young woman on the back of a motorcycle pleading as she's being taken away by hamas militants and we knew there was going to be a high number of casualties at this event and also because what we heard from survivors who had escaped, some in harrowing ways to get out of there. many of them went to this middle of nowhere place on shared cars, busses and taxis so many fled on foot and many talked about witnessing their own friends getting shot at. one said he believes they were shot at by an rpg, not regular rifles. and others said they escaped into the wilderness and hid in the bushes until they felt it was safe to leave. right now the death toll on the israeli side is north of 600. anderson, this might be the biggest mass casualty event in israeli history. i would have to go looking through the statistics but i can't recall another event where 260 people were killed in one place. this does not count potentially others who had gone to hospital with injuries. i do think we should expect that the death toll not only overall but from this specific music festival could rise in the coming hours and days. >> and just to be clear, we're not talking about deaths from a rocket that was fired from a great distance. you're talking about slaughter. you're talking about human people who came and face to face shot up, stabbed, killed these people. >> reporter: yeah, as far as we understand. i don't have this confirmed that a rocket or mortar landed right there. all they mentioned was militants who swarmed this event. one of them talked about using things like rpgs. it appears it wasn't just potential rifle fire. we've also heard from parents from some of these paoeople who attended the festival. as you'd expect, a lot of them are young, in their 20s. one father just gave a press conference a few hours ago saying he was on the phone with two of his daughters who attended the festival together, they called hip m when the militants started coming in. he told them to lay on the ground to lay each other and he said the last thing he heard was a few deep breaths. he says he has no idea where his daughter are, whether they're among the killed, whether they're among the captives. we know quite a few captives were taken from this event. this alone, this attack on a festival by itself, anderson, would be one of the darkest days for israel in its entire history but now it has to be taken into account with what's happening across israel, with all these infiltrations and rocket attacks and obviously this is still a quickly developing situation. >> a slaughter of 263 young people at a dance. thank you. we'll be right back. joining us now is israel's ambassador to the united nations, also the former israeli ambassador to the united states. thank you for being with us. we just learned it's now confirmed some 263 young people were slaughtered at a dance near the border by hamas killers. have you ever seen anything like this? >> only during the nazi era. i mean, they came into this festival, the barbaric terrorists of hamas and they just shot all of them as if they were insects. that's how they treated them. and, yeah, such, you know, being so barbaric with the nazi death squads during the 1940s, that's how they treated the jews and that's why we continue to say this is our 9/11. we are going to shatter the old paradigm and we are not going to stop until we will obliterate the terror capabilities of hamas because such as trocities won't happen again to our people. >> how do you do that given the reality of gaza and gaza city and 2 million people living very close, how do you break the stranglehold of hamas on that territory? >> look, the situation in gaza is a tragedy. obviously i cannot share here with the world, with our enemies, all of our strategic military plans, but we all need to remember that 17 years ago we withdrew from the gaza strip. hamas took over. and since then every dollar that was spent in gaza never -- was never spent on building schools or hospitals or supporting the population. we would like to see them being supported. but instead it was used to build, you know, and dig another terror tunnel or to build the terror capabilities of hamas because we should learn and understand until now hamas is exactly like isis. it's exactly like al qaeda. it's a genocidal islamic movement, a terror organization and you cannot convince them or change their ideology with economic incentives. so right now we all need to be united, the free world, all those who support, you know, liberal democratic values should stand with israel and support not just today but the weeks ahead of us, support whatever we will do there in order to obliterate hamas terrorist infrastructure. >> we've just learned i should point out, mr. ambassador, that at least three americans have been killed following attacks in israeli close to the gaza border according to an internal u.s. memo that we've just heard about. in terms of what happens now, how concerned are you about a widening of this, the northern border we saw obviously in 2006, hezbollah attacking israel. do you expect them -- do you expect the situation on the northern border to change? >> look, we are aware of the long-term goal of iran to arm its terrorist proxies that surround us, like hamas, like hezbollah. that's their long-term goal, how to annihilate the one and only jewish state because they would like to support them also a nuclear umbrella in the future. that's why they transfer weapons and funds to them, but we are making it very clear. obviously, as i said, we are focused on the southern front of hamas. we are aware and we're hear what's happens on our northern front. that's why we also mobilized reservists to strengthen our northern border and we are fully prepared. we also convey clear messages to the lebanese government. we would hold them responsible, accountable for everything that would happen coming from their territory and we hope they will understand our messages because we don't want to expand it and to another front. we just want to bring back the security to israel and make sure that we obliterate hamas' terrorist infrastructure. >> ambassador gilad erdan, thank you very much. appreciate it. we'll be right back. >> thank you very much, anderson. it's obviously a very tense situation on the ground, particularly along the border. we are following the gaza side of the story and what life has been like there for the last two days. >> absolutely, anderson. and when it comes to the goal, the objective inside the gaza strip, for israel there's absolutely the short term and the long term here. first and foremost it's going to be those hostages. prime minister netanyahu has vowed to essentially break the back of hamas, make sure that they can never carry out anything like this again but actually doing that, that's really complicated. take a look. >> reporter: these are the first moments of what prime minister netanyahu warned will be a long and difficult war. air strikes in the densely populated gaza strip that the palestinian health ministry said left hundreds dead and thousands more wounded. israeli's military says it is targeting headquarters belonging to hamas and islamic jihad and released this video. netanyahu vowing to avenge the hundreds of israeli lives lost with more ferocious fire power to come. >> translator: all the places where hamas has deployed, hiding and operating it, that wicked city, we will turn it into an isle of ruins. i am tell peopling to -- tellin people to leave those places now. we will be everywhere. >> reporter: a significant and unprecedented number of israeli citizens were captured according to the israeli military. this disturbing social media video geo located by cnn shows a victim, hands appear to be bound in captivity and hamas claims the hostages are distributed across the strip, israel believes to be used at human shields. israel's human military is pressin pressing on. with air sauassaults under way, they say all options are on the table. thousands of reservists have been called up for the task. israel is telling gaza to clear the way for their operations, ordering families to leave their home and providing locations for evacuations. for most there is no way out. gaza is largely isolated from the world by an israeli air land and sea blockade and egypt's southern border closure. electricity, mostly provided by israel was cut off and internet disrupted. unclear how long services will be severed. and with hamas leadership reportedly going underground, the 2 million people living in the 140 square mile territory have nowhere to turn. fear is growing that an unprecedented attack on israel could yield unprecedented bloodshed in gaza. >> you can only imagine with each one of those air strikes, air assaults being carried out on the israeli military right now, with each one of them families of those hostages, anderson, they could be holding their breath, worried that their families, their loved ones could be caught in the cross hairs. and then there's just the wider picture here. how do israeli live near that gaza border area in areas that were attacked, how do they live in those areas again and still feel a sense of security after this assault? >> there's plenty of residents in gaza who do not like hamas and yet hamas has total control there. it's not as if they have many options of overthrowing hamas at this stage. >> that's the point to remember here, anderson, absolutely. you have 2 million people living inside the gaza strip, a densely populated, deeply impoverished, deeply underserved. ma' hamas did not take their opinion before doing this but they absolutely suffer the conse consequences of any decision by that terrorist organization. but hamas goes underground in gaza. the family, the children, the civilians, those who are going to suffer, they have nowhere to turn. you have that israeli blockade, of course, egypt on the other side is going to potentially be one of the bloodiest chapters in gaza's history just as it has been in israel's. >> i appreciate it. thank you. thanks for joining us today. i'm anderson cooper. i'll have more later from tel aviv. our special coverage continues right now with abby phillip.