Nightline, massacre in las vegas, will be right back. Hows it going down there . Thats good. Lica misses you. Im over it though. laughter thats fine. I miss her more than you anyway. Hey, my window is closing. Yeah thats okay. Alright miles. I love you. phone hangs up yeah i love you too. This is a special edition of nightline, massacre in las vegas. Good evening. Thank you for joining us. Tonight were at the scene of the worst mass shooting in modern american history. My coanchor juju chang is in las vegas. Thanks, byron. The enormity of the staggering death toll still sinking is in here on the vegas strip. The glitz and all the glamour now overshadowed by a lone gunman who sprayed hundreds of bullets from that gleaming skyscraper down on to a packed Country Music concert, turning one of the worlds most popular tourist destinations into a gruesome crime scene. It was a horrifying case of deja vu. We were about 15 feet away from the center stage to the left. Reporter once again people had gathered for music and fun, only to hear this. [ gunfire ] instead. All of a sudden we hear the pop, pop, pop, pop, pop. We just thought it was fireworks. It kept going and going. It was insane. I could see the flashes from the mandalay bay. And i said i see where its coming. Somebody shooting a fully automatic. People just started screaming and running. Reporter at least 59 people killed. Now the deadliest mass shooting in modern american history. Among the victims, lisa romero, a high school secretary. Susan smith, an Elementary School office manager. Sandy casey, a special ed teacher. One offduty officer was also killed. One of my officers was off duty attending the concert and lost his life. Reporter more than 500 people were injured. The horror began nearly 24 hours ago when an estimated 22,000 concert goers packed into an openair venue along the famed Las Vegas Strip for a Country Music festival. They had no idea that high above them on the 32nd floor of the mandalay bay resort, a lone gunman was watching and waiting. Shortly before 10 00 p. M. Local time, headliner jason aldean took the stage. I was videotaping it. And all of a sudden hearing in the background something that sounded like fireworks going off. It was going pop, pop, pop. Reporter at 10 08 p. M. The first shots erupted. All of a sudden you hear the music on the stage stop. Jason stopped singing. And then the lights on the stage went off. Oh, my god. Reporter for so many confusion. Was this part of the show . Thats just a firecracker. I know, but why would they do that . Reporter seconds later the rapid fire shooting starts again. I think someone said theres a shooter. He goes, thats gunshot. And we grabbed each others hands and went running. We have an active shooter. Get down. Well get trampled if we dont go. Reporter the hellfire lasted for minutes coming from just across the street. I see the shots coming from mandalay bay, halfway up. A grandma and a little girl. And the little girl was just asking if she was going to die. She was scared. Reporter ambulances rushed to the scene as bystanders began to triage victims. We need to get people over to the hospital, okay . Okay. Go ahead. Put them all in the back. Put them all in the back. Reporter many plugging Bullet Wounds with their bare hands, turning barricades into makeshift stretchers. Theres many people down. Stage left. Just be advised. Reporter hundreds of victims rushed to five area hospitals. Many with gunshot wounds. It was nonstop surgery after surgery until about 4 30, 5 00 this morning. Reporter the states only Level One Trauma Center overwhelmed by the critically wounded. We brought in extra trauma surgeons, extra Critical Care nurses. Reporter this doctor was the trauma surgeon on call last night. Tell me about the condition of the patients that were coming in. What were you seeing . We were seeing all kinds of injuries. Gunshot to the head, chest, abdomen, pelvis, extremities. Had is something we deal with on a regular basis. The only difference was the higher volume. Reporter at 11 20 s. W. A. T. Teams are able to zero in on the room after the dense gun smoke sets off a fire alarm. Everyone in the hallway needs to move back. All units move back. Reporter they use a flash bomb to enter the room. Breach, breach, breach. Reporter they find him with a cache of 25 rifles and handguns. They identify the gunman as 64yearold Stephen Paddock from mesquite, nevada. They say he checked into the hotel on thursday. His motive remains a mystery. Weve checked all the federal databases and local databases and state databases and we had no knowledge of this individual. Reporter today my colleague matt gutman went into the mandalay bay. You can see the enormous distance between that shattered window where that shooter was perched across that park across the boulevard into that killing field below. What you see down there is a Forensics Team on the ground and those are peoples belongings. Reporter he caught up with mike krunk who was in the thick of the rampage last night. My buddy was like i got hit. Reporter mike used his shirt to keep his friend from bleeding out. You are trying to do triage while the shooting was still going on. No way i would leave my buddy. We knew we were safe. Reporter he eventually got him to a hospital. We need blood. If anybody can contribute blood. Reporter today those wanting to help heeded the urgent calls for blood donations. Some waiting in line up to five hours. This morning President Trump addressed the nation ordering flags at halfstaff, vowing to visit vegas wednesday. In moments of tragedy and horror, america comes together as one. Reporter later he and the first lady led the nation in a moment of silence. Many of the survivors now recounting their race to safety. Memories of other Mass Shootings on their minds. I was trying to be calm. But i thought at the moment i thought of the orlando shooting. We didnt know where the shooter was. Reporter las vegas now sits at the top of a list no city wants to lead. The worst mass shooting in u. S. History. The scenes all hauntingly familiar. From the pulse nightclub shooting in orlando. Another mass shooting in america. Meese are describing this as a mass casualty situation. They said theres a lot of dead bodies in the club. They cant identify anybody. Reporter to the massacre at sandy hook Elementary School. From newtown, connecticut, where today a nightmare unfolded. Reporter modern mass murder in the u. S. Dates back to 1966 when a gunman opened fire from the bell tower at the university of texas killing 14 people below. Since then the pace has quickened. The four deadliest shootings have all happened in the last decade. The pace and significance of Mass Shootings over the last decade in our country is saddening, how normalized its become. Reporter and many including survivors of previous attacks worry it will keep happening. Its haunted our dreams that we would wake up to the news of a massacre like this. This was domestic terrorism. Their hearts are broken. Reporter back in las vegas, hundreds gather for a prayer vigil tonight. Remembering the lives lost while honoring the heroes who saved so many others. And joining me now is russell black and his fiancee brianna skogen. They were at the concert last night in the vip tent which was closest to the shooter. How did that unfold . Initially it started, we heard three, two, three round bursts, pop, pop, pop, pop, pop, pop. It sounded like an amplifier crackling. Reporter you started videotaping. We were taking a photo together. We were going to get one last shot of the stage. And all of a sudden we heard that and i panned over and saw people going around the corner. I looked over, wait, that kind of sounded like an ar weapon. And then sure enough, they were fully automatic, which i was not ready for. I was expecting a few pops. I grew up in kentucky around firearms my whole life. It just was relentless. Were talking hundreds of rounds. I mean, we couldnt move unless we waited for him to reload. Reporter and brianna, how did the crowd react . I mean, at that moment, i thought it was fireworks. And everybody was just kind of unsure what it was. Oh, maybe it was fireworks. Then pop, pop, pop, pop, pop, then everybodys eyes froze. I fell to the ground. People were like ducking for cover. People were getting shot at. Like you ko hear the ricochets around you. It was so scary. Reporter you could see and hear the destruction. And you also saw real heroism, people stepping up into the breach. Absolutely. In a world where everyones kneeling, those First Responders stood up and charged headfirst into that, guns drawn, not knowing what they were going into. Knowing it was a fully automatic weapon. Everyone was crouched, hiding and stuff. I didnt see a Single Police officer take cover. Reporter and you saw people administering first aid. Yeah. Thank god it was a country concert. A lot of exmilitary there. People of all ages just jumping into gear with whatever training they may have had. People putting fingers inside wounds to stop the bleeding, throwing fencing down to try to take multiple bodies out at a time. Reporter you had time to reflect now. You said youve been emotional throughout the day thinking about it. Yeah. We both have. Just kind of comes in waves, huh . Just like when you Start Talking about it again, it just and you replay that sound or someone replays that video and you just hear the gunshots and hear the screaming and it just brings you right back to it. Then its just like a whirlwinded of emotion. Reporter well, its been a lot of trauma for you both. Thank you for tell us us what you saw. Well go back to new york to you, byron. Thng, juju. More information about this shooter. What we know tonight. Having moderate to severe thng, juju. More information about this shooter. What we know tonight. Hthng, juj. More information about this shooter. What we know tonight. Athng, juj. More information about this shooter. What we know tonight. Nthng, juj. More information about this shooter. What we know tonight. Kthng, juj. More information about this shooter. What we know tonight. Thng, juj. More information about this shooter. What we know tonight. Ythng, juj. More information about this shooter. What we know tonight. Othng, juj. More information about this shooter. What we know tonight. Uthng, juj. More information about this shooter. What we know tonight. , juju. More information about this shooter. What we know tonight. 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Details from his brother, his relationship with his girlfriend, what the fbi found inside his two homes. Paddock is solely responsible for this heinous act. Reporter Stephen Paddock with no criminal record is now allegedly the man behind the deadliest mass shooting in american history. From mandalay bay he unleashed a torrent of bullets into a crowd of a Music Festival 1100 feet away. Listen. The sound different from any weve heard from all other recent Mass Shootings because this time a rifle functioning like a machine gun was used. The individual is described as a lone wolf. I dont know how it could have been prevented. Reporter as the death toll has continued to rise, investigators rush to track down anything about the shooter. Were trying to understand whats wrong, what happened. Were still just completely befuddled. Reporter eric paddock, the shooters brother says he has no clue what led his brother on this murderous rampage. Remembering him as a man who grew up without conviction. Steve had nothing to do with any political organization, religious organization, no white supremacist, nothing. As far as i know. Reporter and the fbi says theres no connection to any overseas terror group despoit a claim today by isis. We have determined at this point no connection with an International Terrorist group. Reporter while he enjoyed gambling, his brother said he didnt have a problem and had recently won a 40,000 jackpot. He was a wealthy guy and he liked to play video poker. He went on cruises. He sent his mother cookies. Reporter but in recent months, paddocks financial activities had become abnormal, sending tense of thousands of dollars to someone in the philippines, Authorities Say his girlfriend Marilou Danley is right now. Officials are hoping danley who once worked as a casino hostess for high end players may provide insight. Earlier today authorities descended on the two homes paddock owned in hopes of finding a lead. One in reno. At the other in mesquite they used a robot to take down the garage door. Once inside they found 19 guns. His family says hes a licensed gun owner before this incident. Yes, he had a couple of guns. He did not own machine guns that i knew of. Something incredibly wrong happened to my brother. Reporter what we know now was the murderous attack was planned. Paddock had built up a massive arsenal inside the hotel room. We got shots fired. Sounded like an automatic firearm. Reporter according to authorities he had at least 23 rifles and handguns, one of them an Assault Rifle modified to fire automatically. Some of the weapons were high powered, capable of slicing through police body armor. This is a classic wmd. This is a weapon and a man of mass destruction. Reporter according to authorities, many of the guns were bought legally. The mesquitebased gun shop guns guitars confirmed that paddock had legally bought some guns from their shop. All necessary background checks were followed. He never gave any indication or reason to believe he was unstable or unfit at any time. The general manager said in a statement. We do not yet know if these guns were used in the attack. Nevada has some of the least restrictive gun laws in the country. Theres no limit on the number of firearms one person can possess. And semiautomatic weapons are legal to purchase. Their capability far exsides that of a handgun. When adapted the potential to be even deadlier. As seen in this youtube video. Its a significant game changer in the way we respond to active shooter. Minutes are not quick enough. Reporter tonight the deadly power one man was able to wield leaving us all to ask the question, why did it happen again . Former new York City Police commissioner and abc news contributor ray kelly is with us tonight. Commissioner, tonight what are investigators looking for, do you think . Why . Thats the big question. Why did this individual apparently ordinary person, no kr criminal record, why did he do this . The biggest mass shooting in thi the history of our country. Im sure there are signs that people should have seen. Talk about that. What kind of signs do you think people missed . We dont know what the signs are. They will be hopefully identified during the investigation. But suddenly violent behavior or threats to do Something Like this. These are the types of things that weve seen in investigations of this nature when they go forward. People in your business are students. Youre always learning from these kinds of experiences. Yes. What will Law Enforcement take from this to apply in the future . I think well see more antisniper capacity put in place by Police Departments throughout the country. You have to be a fairly good sized Police Department to do that because most dont have the resources to do it. The new York City Police department has been doing it for years when you have major gatherings. But were blessed with the numbers to do it. But theres no easy way from the ground of getting someone who is shooting from 32 stories up. Commissioner ray kelly, thank you very much. Thank you. When we come back, images of heroism and bravery. The First Responders and civilians who came to the rescue in las vegas. coughsah hey, chad i missed you. Ah i was in the tree watching you, and then i fell. Im not eating pizza from the trash. Then i discovered mucinex. Huge difference. One pill lasts 12 hours, and im good. Oh, here kitty, kitty. Ah not a cat, not a cat why take 4hour medicine . Just one mucinex lasts 12 hours. Start the relief. Ditch the misery. Lets end this. My friend susie cracks and hello sensitive bladder. Ring a bell . Then you have to try always discreet. 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It was omar bradley who said bravery is the capacity to perform properly even when scared half to death. To the brave men and women in las vegas, First Responders, to civilians, thank you. We thank you for joining us. We leave you tonight with their images