Begins right now. Announcer brussels terror attacks. This is nbc nightly news with lester holt. Good evening. Shock and horror but sadly no surprise. Belgium, which for four months has been living on edge and braced for attack, took two devastating hits today, claimed to be the work of isis. At least 31 people are dead, and nearly 190 others are injured, including some americans after suicide bombers struck during the morning rush. Two explosions in the departure hall at Brussels Airport followed by a deadly blast at a busy subway, where commuters escaped through a smoky tunnel. Childs screams of fear. The world once again haunted by images of stunned and bloodied survivors from another brazen act of terror. Tonight a massive manhunt is under way as a chilling photo captures the suspected attackers just moments before they struck, including the one who apparently survived and may be on the loose tonight. We have expanded coverage of the attack starting in brussels with nbcs bill neeley. Terror in the airport terminal. At 8 00 this morning, moments after an explosion. A stroller lies abandoned. A victim is on the ground. A survivor says stay down. Stay down reporter through the smoke, a woman cowers clutching a child. Someone cries, help me. Help me reporter then survivors beginning running, past the bodies and the injured. Some in shock, another calling with news shes alive. Minutes after the first bomb, another explosion near an airport starbucks. And hundreds are running for their lives. Others fled to the tarmac and safety. There was no safety inside with fire from the first explosion, Ceiling Tiles falling, Dozens Injured and at least 11 dead. And it wasnt over. Another bomber was about to strike in the very heart of brussels, near the European Unions headquarters. 10 after 9 00 and deep underground, a massacre in the brussels metro. A bomb has just exploded. Dozens flee through the darkness. Its terrifying. They left behind a mangled train car, at least 20 dead. Horror on the morning commute. Many of those on the train and at the station here have been reading about the first attack at the airport on their phones when the bomb here went off. An american on the next train felt the impact. We felt a little gust of wind. My ears popped, and we heard some thudding. Reporter isis claimed the attacks. Police believe these are the airport killers wheeling bombs in suitcases. Two blew themselves up. The third man in the light jacket is on the run. As night fell, police raided a brussels apartment. Police helicopters are in the air. Their search for one of the two terror suspects has now narrowed to this street with Police Snipers and ambulances also standing by. They found explosives, an isis flag, and bombmaking material, but no suspect. Belgiums Prime Minister called this a dark day, and all day president obama has been kept briefed. More than 200 were injured, many by shrapnel. This nail is in a mans chest. At least four americans were wounded. Three are mormon missionaries in the hospital with shrapnel wounds and burns. One had also been a block away from the Boston Marathon bombing. A couple from kentucky are still missing tonight. Todays attacks come just four days after the arrest in brussels of the paris massacre suspect, salah abdeslam. And so many questions here tonight, lester. How big is this new terror cell, and who exactly is on the loose . Belgian tv reporting tonight that a cab driver told police he dropped off three men at the airport who had great difficulty getting heavy bags out of his car. He told police and then led them to the house where the police found those explosive materials tonight. Lester. Bill, you showed us that photo of the airport attackers. Now an allout manhunt is under way for a suspect spotted on that surveillance photo at the airport along with two men believed to be the pair of suicide bombers who struck that location. Authorities are digging for whatever possible terror connections they may have. Nbc news chief Foreign CorrespondentRichard Engel tells us more. Reporter these are the men, belgian prosecutors say, who were responsible for todays atrocities at the Brussels Airport. The two in black probably blew themselves up with suitcase bombs soon after this image was recorded. Both are wearing gloves on their left hands, and this man in the hat is the target of an urgent manhunt. Now nbc news is learning about a new warning, that an isis terror wave could be coming soon. A senior u. S. Counterterrorism official told nbc news brussels was likely just the beginning. U. S. Intelligence Officials Say that their working assumption is that todays attacks were carried out by the same isis network behind the coordinated attacks in paris last november. And the attack on a french train, foiled when offduty u. S. Servicemen tackled the gunmen. They also said that todays atrocities in the planning stages for some time may have been thrown into high gear by the arrest last week of this man, salah abdeslam, one of the accused paris bombers. Tonight, belgian Authorities Say abdeslam is cooperating with interrogators so his former colleagues may have wanted to strike before they got pulled in. But the real shock today is just how predictable it all is. This is where intelligence meets up with Law Enforcement. They dont have the quantity of resources that we have in the united states. Reporter thousands of europeans have traveled to fight with isis in syria and iraq, and hundreds have returned. European security agencies have thousands on watch lists. Isis members names are even listed in documents allegedly stolen by an isis defector. How big of a problem is isis in europe . Its a very big problem. Clearly there is a Strategic Campaign going on right now. Reporter abdeslam was caught in the very brussels neighborhood where the paris attack was planned, just a few doors from his home. Yet it took police four months to find him. And after todays horror, the question is how many more terrorists are ready to strike . Richard, youve laid out what theyve been through the last four months. Theres been this sense of dread. Any suggestion that the u. S. Intelligence had some prior warning that something was about to happen . Yes. A senior u. S. Intelligence source told me that the American Intelligence Community three to four weeks ago, based on chatter that they were receiving, which is communications that are intercepted, they believed that there was going to be an imminent attack somewhere in europe. Unfortunately the intelligence wasnt more specific than that. The source said all the americans could do was pass that information on. And what theyre now trying to figure out is what happened today . Was that the attack they had been expecting, or is there still one to come . Thats the frustrating part. No specifics. Only a hint of something to come. Richard engel, thank you. Now to our exclusive eyewitness accounts from inside the Brussels Airport of the exact moments the bombs went off. An american couple who in a split second found themselves first ducking for cover and then running for their lives. Nbcs Kelly Cobiella has their harrowing story. Reporter a packed departure hall, then suddenly smoke, debris, and screams. In the middle of it, american jeff hoffman. There was dust and debris, and there was the smell. Hoffman, a consultant for nato living in brussels, was dropping off his girlfriend for a flight home to the u. S. Bag tags printed, luggage paid for, and then the blast. The first one was screaming. Jeff felt the shock wave and pushed his girlfriend under a ticket counter. Then the second explosion. My thought at the time was thats one, thats two. Threes coming. Maybe even four. And given what we know about what happened in paris, i thought theres a good chance im going to start hearing rifle fire. Reporter he saw a single soldier and made a run for the door, his girlfriend behind him. Hidden among the debris on the ground, what youre seeing were people kind of lying and not moving. The tragedy, the bodies, the blood, the destruction. I wouldnt wish on anybody to see. Reporter jeffs brotherinlaw survived 9 11. Jeff was in brussels for the lockdown after the paris attacks. In istanbul, a week before a suicide bomber killed tourists in january. And now this. I lived. Shareen lived. But i saw people coming out who they were not going to live or were going to be in a remarkable amount of pain. Those people are going to have those lives forever altered, and in some cases there are loved ones who left this morning and are not coming home tonight. Kelly cobiella, brussels, belgium. We all feel a sense of vulnerability after these attacks. Airport security at home is being examined but through a different lens tonight after the brussels attack happening in the ticketing check in area, a part of the airport with the public and their belongings are not normally screen. Meantime, Homeland Security says its planning closer scrutiny of belgian passports while its also working with local Police Departments to strengthen the Security Posture at airports. Nbcs tom costello with late details. Reporter at airports across the country, the morning rush brought beefed up, visible security. The tsa screens nearly 2 million passengers a day at 440 airports nationwide. At newark airport, the port authorities heavily armed tactical unity in a show of force through the terminal. In miami, dog teams and squad officers set up roving checkpoints with a group of belgians preparing to fly home. I like to go on trips, but were scared. We said to each other, this is the last time were leaving home. Reporter also in miami, another belgian on his way to ni nicaragua for his wedding. I think fear would be the worst response. Reporter overseas, u. S. Bound flights are getting added scrutiny at those airports, from Charles De Gaulle in paris to germany. Terrorists have repeatedly demonstrated aviation remains an attractive target. 250,000 people fly into the u. S. From foreign airports every day. Former tsa chief john pistole. The concern has always been, as evidenced by the Christmas Day bomber and richard reed, the shoe bomber, and other plots that foreign airports are perhaps not as secure as u. S. Airports. Reporter the u. S. Veteran Security Experts say the airports are most vulnerable between curbside check in and the tsa checkpoint, exactly where the Brussels Airport bombers struck. You just dont have enough military or police in these areas to really show do a show of force on a 24 7 basis. Reporter by a strange coincidence, the current tsa chief was in brussels today meeting with his european counterparts when the attack happened. Homeland security today is once again reminding everyone at the airport who works here or travels through an airport, if you see something thats out of the ordinary, say something. Lester. Always good advice. Tom costello, thank you. Lets bring in if we can, michael leiter, former director of the National Counterterrorism center. Hes now executive Vice President of leidos, which does National Security work for the government. Michael, whats your take on what we are witnessing today and the impact Going Forward . Lester, i think what is so remarkable here is that we had the attack in paris, the arrest three days ago, and then officials still were not able to disrupt this cell. That tells us that the network is more sophisticated and likely communicating in ways that are making it possibly immune and in a very, very dangerous sense. So what that consequence is, i think, is really telling for europe, and i think we will see over the coming weeks a change in europe politically to tighten borders and that they really need to now create a more cohesive Intelligence System that currently does not exist across the continent. Michael leiter, appreciate your analysis. Still ahead tonight, president obama facing criticism for his response to the brussels attacks, why his day at the ballpark in cuba with raul castro is rubbing some the wrong way. Also the fiery reactions to these attacks from the candidates in the 2016 race. Well be right back. The attacks in brussels rocketed across this country moments after they occurred, including the campaign trail. All the candidates weighing in with very different reactions, and president obama in cuba vowing to fight terrorism but not changing his plans today. Something thats not sitting too well with some. We have all the political fallout coverage starting with nbcs andrea mitchell. Reporter on a day of anxiety and fear in europe, the president did not change his schedule, wrapping up his cuba trip by joining raul castro as tampa bay challenged cubas national team. Before the first pitch, a moment of silence for brussels. President obama said he never thought of not going. You want to be respectful and understand the gravity of the situation, but the whole premise of terrorism is to try to disrupt peoples ordinary lives. Reporter at the game, obama and castro, despite their differences, just two fans sharing a national pastime. Almost catching a wave. In the stands, a lineup of big hitters. Dave win field, dear eck jeter, plus key players on the National Security roster, a starkly different setting this morning at the u. S. Ambassadors residence, a secure call to belgians Prime Minister. This is another reminder that the world must unite. And this from the first lady. We are outraged and heart broken over the horrific attacks today in belgium. Reporter tonight raul castro saw the obamas off at the airport. The president sticking to his next stop, a state visit in argentina. Andrea mitchell, nbc news, havana. Reporter im hallie jackson. The images from brussels, like paris and San Bernardino before, now bringing into focus the dramatic differences between the parties frontrunners. I would close up our borders to people until we figure out what is going on. I think there are a lot of things we have to do to intensify our efforts. I think closing our borders is not one of them. Reporter for Hillary Clinton, a chance to prove her National Security credentials. For donald trump, an opportunity to seem more president ial one day after calling for controversial cuts to nato based in brussels. A huge amount of uncertainty into the system at exactly the moment where we need intensified cooperation. Reporter trump, hoping to project strength, even where his opponents see weakness, like ted cruz, taking his own hardline stance, a striking one. Demanding Police Patrol and, quote, secure neighborhoods of american muslims. Anywhere where there is a locus of radicalization, where there is an expanding presence of radical islamic terrorism, we need Law Enforcement resources directed there. Reporter civil Rights Groups and cruzs rivals taking aim. Because you happen to be of another religion that somehow you have evil intent is just irresponsible in my opinion. It wroould be unconstitutional. Trump agreeing with his closest competitor. National security again forced to the front of this president ial race. Hallie jackson, nbc news, new york. Were back in a moment with some of the days other news, including the death of a highly controversial political figure. Well have more on the brussels terror attacks in just a moment, but first some of the days other news. Rob ford, the former toronto mayor whose misconduct made him internationally famous has died. He was battling a rare aggressive form of cancer. Fords scandalplagued time in office made headlines including in 2013 when he admitted smoking crack cocaine while in office. His reelection bid was cut short when he was diagnosed with cancer. Instead he ran for his Old City Council seat and won in a landslide. Ford was 46. Back to the campaign trail and the race for president. Both donald trump and Hillary Clinton hope to expand their leads tonight as three states in the west hold contests. Democrats and republicans are voting in both the arizona primary and the utah caucuses, and the democrats have another battle tonight in the idaho caucuses. When we come back, the enormous international outpouring of support for brussels in the wake of terror. We at t begiing oa 3 so waterevolion icalifnia. Tr 03 calirnia trav to t whithousehow tyll e new nextt 6 3 sol the ought nt cl here at home and around the world, in french, in flemish, in english and in dozens of languages and sometimes just in colors, people are standing in solidarity with the people of brussels tonight as nbcs Anne Thompson shows us. Reporter belgium wrote its sorrow in two languages, french and flemish. The world responded in one, support. The chair asks that the house now observe a moment of silence in memory of the victims of the terrorist attacks in brussels. Reporter traveling in the middle east, the European Union foreign minister. Today is a reporter couldnt control her grief. When words failed, images helped. The black, yellow, and red of the belgian flag lit the eiffel tower. Romes trevi fortunate, the brigade of berlin. Even the worlds tall et building in dubai, a muslim city. Flags flew at half staff over britains downing street, and 1600 pennsylvania avenue. Social media wrapped itself in the belgian tricolor too. A french newspaper tweeting empathy to its wounded neighbor. Others using belgian comic book legend to express their sorrow. Translator why do we have to stay inside, asked this man . Then these guys have won. Today, simple things are acts of defiance as the world now tries to help belgian mend its heart. Anne thompson, nbc news, new york. That will do it for us on a tuesday night. A program note. My colleague matt lauer reports live from brussels tomorrow morning on today. Ill see you from there tomorrow night as well. Stay tuned now on many of these nbc stations for a second half hour of nightly news. Im lester holt. For all of us at nbc news, thank you for watching and good night. Brussels terror attacks. This is nbc nightly news with lester holt. Good evening, everyone. We continue in our special breaking News Coverage of the terror attacks in brussels. Dozens killed and hundreds wounded including americans. Scenes of carnage from the airport and the subway that have stunned the world. The suspected bombers caught on camera. And at this hour, a massive manhunt is under way for the one suspect who apparently survived and remains on the loose. There have been raids going on across belgium today. Thats where we begin with nbcs keira simmons. New information just coming in. Keira what can you tell us . Reporter well, good evening. Lester. Tonight nbc news has learned that authorities believe they have located a bombmaking