He has new information just coming in. Keir, what can you tell us . Reporter well, good evening, lester. Tonight nbc news has learned that authorities believe they have located a bombmaking factory and have found additional suitcase bombs, one at a house near the airport, where this day of horror began. Tonight police are hunting this man, as yet unnamed, seen in the airport with two others. Believe blew themselves up moments later. The checkin area filled with smoke. Stay down, stay down. And childrens strollers abandoned. A woman in shock holding her child, cowering in the lots of people whose hands were covered with blood, and everyone is crying, and, yes, its the first time i saw such a thing in my life. Reporter many injured, bleeding and many dead. Killed by bombs packed with nailed, isis claiming horror. Outside shattered windows and fractured nerves. All the luggage stays here all the luggage stays here reporter hundreds fleeing on to the tarmac, smoke billowing from the airport building. You just feel like a wave, a wave go through your body. Reporter then an hour later more carnage. A subway cars doors blown out just as the plain was pulling out of the station. Passengers escaping along the track while heard along the tunnel screaming. Everyone was really shocked. They couldnt even describe because i asked two or three times what happened . What happened . And people couldnt really they were shocked and scared and i said, okay, someone said there was a bomb, an explosion. Reporter americans were among those injured in todays attack and some still missing. No one has heard from stephanie and justin schultz. Their family increasingly worried. And tonight those behind the attacks may raid discovering improvised explosive devices, chemicals to makes more bombs and an isis flag. Tonight a huge manhunt is under way, and this afternoon there were reports of lines of cars at the border undergoing security checks, but there are increasing criticism, lester, of the security failures that some people believed have occurred here, and when we crossed the bothered tonight, we saw no checks, no police. Lester . Some powerful images and stunning sounds there. Keir, thank you very much. There have been no reports of any americans killed in these attacks, but a number of americans were injured, including a group of mormon missionaries. Nbcs Miguel Almaguer has more on the americans in belgium and their families anxiously awaiting word back home. Reporter at least six americans were injured in the attack, belgium. Here at home their families waited desperately for word from their loved ones. The middle of the reporter chad wells son mason suffered seconddegree burns and was hit by shrapnel. The 19yearold was at the airport, along with mormon missionaries richard norby, joseph empey and fanny rachel plane, all recovering. Ironically mason was in paris when 130 people were killed and also survived the attack. I think that experience of the chaos and civil unrest prepared mason for whatever he experienced today. Reporter for parents News Campaign stakingly low. Lauren cleary, monica hall and kate duffy, students from quinnipiac university, were also at the airport during the attack. Janet cleary got the call at 3 00 a. M. That lauren and her friends were all safe. She called and crying hysterically, that you know, that she that there was a bombing, that she was at the airport and a bomb went off. Reporter some in belgium. Universities like wisconsin, illinois and northeastern thankfully tweeting everyone is safe. Meg hilling is with the group of 16 journalist students at mizzou. I do feel safe to an extent. I mean, its made me realize that anything can happen anywhere. Reporter tonight most americans in brussels are safe. Their families thankful and praying for those killed, injured and still missing. Miguel almaguer, nbc and Airport Security here at home is being examined through a different lebs tonight after the brussels attack. As we had said earlier, it was in the ticketing checkin area, a part of airport where the public and their belongings are not normally screened. Typically in american airports. Nbcs tom costello is working his sources. Tom, is there a rethinking now of maybe the whole airport needs to be secured . Reporter well, i think that that would be an ideal situation, lester, but the challenge, of course, is you simply dont do that, and you dont have necessarily the money to do it. There is a reality here that there are tight budgets across the country. You know, theres been a great deal of concern all along that if there is a soft target, if you will, at the airport, not that the whole thing isnt a soft target, but they are particularly vulnerable between the parking garage and the checkpoint. Some Security Experts say, listen, what really needs to happen is a Robust Police or military presence in that zone between the curb and the checkpoint. The more officers you have, heavily armed officers, whether in europe or here in the states, that in and of itself seems to act as a deterrent, and then in addition the more people who are speaking up and saying something that looks like its out of the ordinary, that also helps. A couple of other moving parts i do want to pass along to you. The embassy in brussels, the u. S. Embassy is know asking u. S. Government employees not to come to bruce els for at least a week until the 29th because of the situation there, and American Airlines is other airlines are certainly not going to fly in tomorrow. The airport is closed. Thursday is out of the question. Friday looks iffy, but that would be the earliest at best because of the situation at the brussels airport. The forensics investigation and the rebuilding. Here in the u. S. , Homeland Security is also saying it has no credible information right now about any potential threat against u. S. Airports, but it takes all threats very seriously. Back to you. Tom costello in washington, thank you. The deadliest of todays attacks in brussels was the bombing of a subway train. Security experts say that reflects that reflects a sobering reality, more people are killed in terror attacks on the rails. Our justice correspondent Pete Williams has more on steppedup security in u. S. Cities. Reporter in new yorks times square, extra police swarm in with 50 officers deployed to the subway station there. On bridges and tunnels more random checks of cars and trucks. On commuter train systems from los a scramble to turn out a visible show of force. Nationwide fbi agents are stepping up surveillance of terror suspects on the lookout for possible copycat attacks here at home. U. S. Officials tonight say theres no known threat of a brusselsstyle attack here, and the experts say the security picture here is far different. Police in europe are overwhelmed trying to track the nearly 7,000 people who have been to train with isis compared to the roughly 200 who have gone or have tried to go from the u. S. Some of the countries in europe have unique challenge. I think its probably because of their close proximity to some of the countries of concern. And the fbi has proven adept at stopping potential attacks here but u. S. Officials say they face one big challenge, their european counterparts do that make it harder to tracks the use of encrypted apps, disposable phones and other ways to communicate that cannot be monitored, and a former Homeland Security expert says start over much of europe working hard since 9 11 to prevent terror attacks. The bombmakers, however, are very adapting, too. So this is not a static situation. It it will keep moving. It requires the United States security to keep improving. Other factor. American officials to develop and maintain good relations with the u. S. Muslim population whose members often provide a warning of potential trouble in their own communities. Lester . Pete, you mentioned copy cats. How concerned are you that what happened in brussels might trigger something here . Its something that they want to watch for, but their general view is that people here in the u. S. Who are going to care out terror attacks are on their own wavelength and they dont cake their cues from oversees if they already have some plot in mind but nonetheless they want to make sure that Something Like this isnt a trigger point here. Pete williams, lets bring back Michael Leiter now executive Vice President of lidos which does National Security work for the government. Michael, what are you hearing from the Intelligence Community after the attacks about what heart and what things may have raised the hairs on the backs of next before today . Counterterrorism officials have really been incredibly nervous since paris and San Bernardino, and its generally because they dont think they are seeing everything. They understand how big this radicalized population is and parts of western europe and they simply arent seeing the communications. They dont understand the networks in a way that they have previously so they feel more blind and really they have for five or ten years and thats got everyone nervous. They dont see the same activity in the United States, but old saying in intelligence goes you dont know what you dont know. Pictures are so chilling, and it makes us all feel vulnerable here in the u. S. , but the simple fact, are they fighting a different kind of war against isis in europe than what weve seen, San Bernardino attack . It really is different, lester. What we see in western europe are largescale, sophisticated networks where there is training and coordination to make the sorts of ieds that were used today, in the u. S. It has been much smaller, home grown inspired simply using small weapons. It can obviously kill people but generally can be more easily detected by officials, so europe has a larger problem, and they real very a more sophisticated problem than we have in the u. S. Here today. Youre keir simmons was on a short while ago reporting that they found what may be a bomb explosives. Are those sorts of things as easy to get in this country as they might be in europe . Well, regrettably the precourseors for these homemade explosives are generally made available. Often its Hydrogen Peroxide and some other readily available tools, but actually making those weapons is a bit of a challenge and in most instances, like we saw london in 2007, the bombs dont work, so i think what we have in belgium is, again, a group that has been welltrained, possibly in syria, and has practiced enough that right. So far we havent seen in the u. S. Michael, always appreciate your perspective. Thank you. Todays attacks in brussels have a huge impact at home in the race for president p. Of the candidates are reacting to all therefore, and they are react npg different kinds of ways. The man they all want to place, president obama, is taking heat for his response to the attacks while on his trip to cuba. Nbcs Kristen Welker is on the campaign trail and tells us more. Reporter as terror again overshadows the campaign trail, the sharp contrast between the two frontrunners taking center stage. Donald trump calling to close up u. S. Borders and other extreme measures. You say you would even go further than waterboarding, is that right . Absolutely, absolutely. How far would you go in. Id go further. Reporter Hillary Clinton calling that high does the wall have to be to keep the internet out. Reporter for trump an opening to answer critics who say hes not president ial, for clinton a chance to showcase her Foreign Policy experience. Regardless of what the campaign has become about it, will now revert back to National Security. How is this person as president going to keep you safe . Reporter meanwhile the gops number two ted cruz trying to match trumps hard line calling for police to patrol neighborhoods of american muslims. Todays attack underscores the need for a strong commander in chief. Reporter a position that drew criticism from republican and democratic candidates. Because you happen to be of another religion that somehow you have evil intent is is just irresponsible. That would be unconstitutional. It would be wrong. Reporter meanwhile, the current commander in chief addressing the tragedy during his historic trip to cuba. And this is yet another reminder that the world must unite. Reporter and despite criticism from republicans he made no attending a baseball game with his cuban countersglarts they cannot defeat america. Reporter and now defending america in sharp focus once again. Kristen welker, nbc news, seattle. Still ahead tonight, inside the tunnel as passengers flee for safety and the terrifying moments bombing what does fresh epcot mean . Maybe its sampling seasonal dishes. Enjoying handpicked music or seeing locally grown topiaries. Whatever you pick here, the Epcot International flower and garden festival. Is certified fresh epcot. Experience a year of fun and all four theme parks with a florida resident annual we are hearing incredible stories of survival in the wake of the terrorist attacks in brussels. Evan lamios, a new jersey native was on the metro train behind the one that was hit by a bomb blast this morning. What followed was a frantic evacuation of passengers through the smokey tunnel, and evan caught it all on camera. Here he is in his own words. This morning i was on my way to work. I went via metro. I was reading on my phone about some explosions at the airport, so immediately i knew there was something going on in the country, and then suddenly there was kind of a blast of air, and my ears popped. We heard some loud thuds that seemed to be in the distance, and and the metro stopped, and and there was an announcement that came over the speakers saying that there had been a disturbance on the metro line, and at that time people were on the metro. People were starting to talk about the fact that there had been an attack at the airport. People seemed to be a little bit disturbed and a little bit concerned. They opened the very last door and installed a ladder and had us evacuate out on there was smoke that collected in the metro tunnel, so as we were exiting the metro it was clear that something severe had happened. When i realized that there was something really going wrong, i had no idea that it was as close as it was. I thought it must be pretty far away and they are just trying to be extra careful in evacuating us on the track. Im still waiting in a sense for the emotion to hit. I know i was close to something really horrible, but it hasnt really entirely sunk in yet. These people who have been injured and who have died today have died in a way for our freedom, and i think we should honor that by not letting it strike terror in our hearts. Evan lamos in his when we come back, how will this day of Impact Security ar with you for a long time. Were back with more of our breaking News Coverage of the terror attacks in brussels. We want to bring in now nbc news analyst christopher dickie, the news editor for the daily beast and is based in paris. Christopher, after the paris attack there was a lot of soulsearching about the open borders at the eu, about security cooperation. What happened to that assuming its picked up, where does it go now . Well, it was and is an ongoing conversation. Theres always talk about how you can have better intelligencesharing. How the police can Work Together better, but were talking about 28 Different Countries here with very different culture, very different legal cultures and police cultures. Its very, very hard to get them to coordinate coordinate. The idea that you can open up all the borders of europe but not have a single strong federal police force and federal Law Enforcement system was always a fairly impractical why the and now the chickens are coming home to roost to use a terrible cliche. We talked a lot about vulnerability today, but is there a higher sense of it given the fact in many ways they saw this coming in the climate was right for this, an and yet it happened and even with knowing it was going to happen they couldnt pinpoint it . Well, thats right. I mean, you get this chatter. You hear that happen, and, frankly, just the mood in the Intelligence Community was that things inevitably were going to happen. In fact, on friday morning i was talking to one of the french counterintelligence specialists, one of the top guys and i said when do you think the next big attack is going to be. He just looked at me and said soon. It was always noon that there was always going to be some kind of attack, that isis was going to try to strike back, not just for the arrest of this guy on friday but because this is a war that they are waging against the United States and europe. All right. Christopher, good to talk to you. Thanks so much for being with us tonight. Were back with finally tonight, the horror we feel after the brussels terror attacks has sadly become part of a new normal. Maybe its not even new anymore. And yet even under what some call a constant threat of terror the world in which we live might still find a way to carry on. Heres our harry smith with some final thoughts. Is it, folks. Explosions rocking the airport and the city subway system overnight. Reporter we click on the tv in the morning to see whats new, and we are stunned, as we watch the coverage we connect our own dots. The arrest last week of the terrorist in belgium, the guy who got away from the attack in paris. We remember belgium, that neighborhood, molenbeek, trouble there. Did the belgian authorities miss something . Did they not turn that place inside out . And if they did, then this is worse than we want to believe. The numbers, the resources, the holy hell whenever possible. We hear the eyewitness accounts. The shock and impact, the shock wave that hit just was like nothing ive ever felt before. Reporter just another day stories turn into tales of survival. Our guard is up again, just like every other time this happens. California, paris, we hold our loved ones closer and realize this feeling will fade in a few days, but we also now know this will happen again. Harry smith, nbc news, new york. Let us honor the strength and resilience of this day, too. Thats going to do it for us on a tuesday night. A program note. Matt lauer reports live from brussels tomorrow morning on today. Ill see you from there tomorrow night as well. Im lester holt. For all of us at nbc news, thank you for lights, camera, access. How does it feel, first night down