Out, Ceiling Tiles collapsed as passengers fled in panic. A young woman cried for her mother. [cries] and a man shouted. But there were no soldiers to come to their rescue. In the confusion, the survivors streamed outside looking for help. Some of the injured were wheeled out on luggage carts. All the luggage stays here. All the luggage stays here. Reporter the area outside the airport became a tangle of injured bodies. Those who came to help were quickly overwhelmed. After the first explosion in the departure area, a second one followed. It was very loud. It was not something that fell on the ground. You felt kind of shocked. Terrible thing. An explosion. Reporter the explosions were right in front of me, this woman said. Look around. Isis claimed responsibility quickly for the attack today, warning of more dark days ahead. Belgian Police Released this photograph of three suspects. Look at the two on the left, casualty pushing luggage which officials believe were loaded with explosives. Theyre wearing only one governor each, possibly to conceal a detonator. Both men were killed in the attacks. The third man, in the hat, has vanished. According to police, he left his luggage and is on the run. Another bomb was found which police detonated by a controlled explosion. This afternoon Security Forces conducted raids in the brussels neighborhood of shaerbeek and found two more explosive devices containing nails as well as chemicals and an isis flag. One of the doctors who dealt said he hadnt seen any bullet wounds, only injuries caused by the blast. The attacks in belgium come just four days after Salah Abdeslam was caught in a Dramatic Police shootout in brussels. One of the ten paris attackers, abdeslam was the only one to survive the Police Dragnet and evade capture for four months. After his arrest, abdeslam had promised new attacks, heightening fears among Security Forces that the militants reach into europe is deeper and larger than they knew. Now Counterterror Police are conducting further raids tonight, scott. Theyve launched massive manhunt to find that missing third suspect. After raids in brussels uncovered two more bombs today, police fear militants may have been planning even further attacks. Pelley Charlie Dagata at the airport for us tonight. Charlie, thank you. So why brussels . Well, there are several possible reasons. Its home to the nato alliance, and it has its own population of islamist extremists. Today at least 20 of the dead were killed in the subway station that serves the European Parliament, and becca Becca Pizzi Allen pizzey is there. Reporter minutes after an explosion ripped apart a rush hour subway train in central brussels, passengers scrambled to safety in near pitch dark. Smoke billowed from the station entrance as the days commuters streamed out. The explosion went off barely an hour after the airport attack. The mangled remains of the cars were graphic evidence of why there were so many horrific karmities. Some of them had to be treated in the street. Many had what appeared to be serious head injuries. Emmanuel batiot arrived during the aftermath. You see it in a movie, but you cannot imagine when you see people yelling like they were. Like they are going to die, and you dont know. Reporter Lachlan Carmichael was on another train in the tunnel. And we received a big blast of air, and the train stopped. Your attention, please. And we had the normal recording announcement. Weve just had an incident on the line. Passengers told me inside they felt very nervous, very worried. Reporter police and soldiers flooded the area. The station is only about 400 yards from the European Parliament building and the area is considered among the most secure in the belgian capital, but this is a city that lives with major terrorist threat in its midst. It emanates from here, the suburb of molembeek, known to have sent at least 30 foreign fighters to syria. Many of the paris terrorists lived and plotted the november attacks in the neighborhood. In the wake of todays bombings, the authorities asked people the move around the city as little as possible. That has now been lifted, scott, but the Belgian Crisis Center attacks is real and serious. Pelley allen pizzey in brussels. Allen, thank you. We know of no americans killed today, but several were wounded. Jim act has the latest. Reporter Carolyn Moore from kentucky was with her daughter stephanie when the bombs exploded at the airport. Stephanie is now missing. My husband called the american embassy, and he said theyre looking for her, too. Did you receive information from. I havent gotten any information from anyone. Reporter the injured include three mormon missionaries from utah, 66yearold richard norby, joseph empy and mason wells. All three are recovering from their injuries. Friends tells us wells was also at the Boston Marathon bombing lancier ear paris attack. A u. S. Air force lieutenant colonel, his wife and four kids were also injured. Were told some were seriously this man, seb bellin is a belgian businessman who once played College Basketball for Oakland University in michigan. His father spoke to his son in the hospitals. Well, he saw people dying. He saw people dead and people dying. So thats. Im sure that will stay with him for the rest of his life. Reporter and then there are the near misses. These three students from Quinnipiac University in connecticut are studying abroad. They were at the airport traveling for spring break. Kate duffy spoke to us by phone. There was a huge ball of fire like 50 feet from us, and it absolutely was insane. Reporter professional basketball fans will be relieved to hear that while former nba allstar Dikembe Mutuombo was in the airport at the time of the bombing, he is reporting on his Facebook Page he was not injured. Pelley jim axelrod, thank you. Well, here at home Law Enforcement went on high alert, and Michelle Miller has that. Reporter just before rush deployed an army of counterterrorism officers from three elite units, including its hercules team, specially trained to protect the citys most sensitive target and transportation hub. New York City Police commissioner bill bratton. The timing of this event allowed us to hold over the morning tours of duty on all of those units, so we have literally double the amount of officers available to us this morning. Reporter thousands of commuters filed past heavily armed officers and were thought to have their bags searched. Its comforting. Very grateful to all of them. Reporter in los angeles, Police Presence was beefed up at union station, the largest rail terminal on the west coast. Los Angeles Police chief charlie beck. We want to have high visibility. We want to make sure that our Critical Infrastructure is safe. Reporter in chicago, police had k9 units on the platform when train arrived, and in washington, d. C. , the metro f. B. I. This morning to make sure her officers were doing all they could to protect passengers. Mary battle and her family visiting from florida witnessed the show of force in times square. Im hoping that with the extra security here that this is going to be one of the safest days. Reporter scott, while there is an arm presence in times square above ground, the nypd announced that it will be. Aing up patrols whose sole purpose will be to guard the citys busy underground sunway system. Pelley michelle, thanks very much. The man who runs counterterrorism and intelligence for new York City Police is Deputy Commissioner john miller and a former Senior Correspondent here at cbs news. John, is isis coming here . Reporter well, isis is already here. As isis has developed as an organization, scott, what weve seen is inspired attacks. Theyre basically advertising through social media, theyve weve seen arrests in those cases. Enabled attacks where theyve chosen to targets and spoken to people directly over closed social Media Channels where theyve said, heres the target, go do it. What we havent seen is directed attacks. Thats what we saw in paris. Thats what we just saw in brussels. And thats what we have to be prepared for obviously. Pelley what did you learn from the tactics that were used today . I think we learned once again that you have rudimentary tactics. Were talking about fairly large bombs when you look at the damage and assess the casualties, but basically terrorism as we see it here, explosives, or as we saw in paris, explosives with active shooters is a lowtech, lowcost, but extraordinarily highimpact venture. Pelley since paris over these last four months, islamic extremists in brussels have been under withering scrutiny. Raiding their homes, tapping their phones. How can this happen with that much scrutiny . Well, a couple ways. One, theres an opposite argument that the intelligence was pretty good, they managed to find their way just a few days ago a secret safe house, hit that location, actually come up with a mastermind who was not just a mastermind of planned attacks in western europe and brussels, but attacks that have already happened in paris some thats very good intelligence. On the other hand, there was a shootout. There was an officer wounded, a couple individuals got away. So you look at that. But i think the real point here, scott, is were looking at what we call going dark, which is whether its the app telegram, which you featured on 60 minutes this week, which was all encrypted, or the app wicker, which comes out of san francisco, not russia, that is all encrypted, we are seeing not just iphones that cant be cracked, but entire Communications Systems that are were seeing those become the primary tools of terrorists. So when you ask a question like, how could they miss this, the technology is becoming a big enabler. Pelley john miller, Deputy Commissioner of the nypd. John, thank you. Its been only four months since the isis assault on paris that killed 130. Many of those terrorists came from that same brussels neighborhood that allen pizzey showed us. Holly williams is in paris tonight. Holly, what are the connections between paris and brussels . Reporter well, scott, there is suspicion, but at this point no confirmation, that the two are closely linked. Just four days ago Salah Abdeslam, the alleged logistical planner behind the paris attacks, was finally captured in belgium, and when the Belgian Police raided an apartment last week in brussels, they found ammunition an isis flag and abdeslams fingerprints. Imminent. Pelley but all of europe has been on alert since the paris attacks. How could this happen today . Well, scott, we dont know if there were any intelligence failures, but certainly one criticism that is leveled at european intelligence officials is that they dont share enough information because they dont trust each other. And thats a very big problem. Because within europe you have open borders and visafree travel between countries. Some of the men involved in the paris attacks were able to go to syria, fight or receive training from isis and then return home, traveling through europe apparently unnoticed. The big question now, especially after todays attacks, is how many more young men may have done the same thing. Pelley Holly Williams in paris for us tonight. Holly, thank you. How did isis succeed today with police hot on their trail . Well have that next when this expanded edition of the cbs if you suffer from a dry mouth, then youll know how uncomfortable it can be. But did you know that the lack of saliva can also lead to tooth decay and bad breath . Well, there is biotene, specially formulated with moisturizers and lubricants. Biotene can provide soothing relief and it helps keep your mouth healthy too. Biotene, for people who suffer from a dry mouth. So protect them with k9 advantix ii. It kills fleas, ticks and mosquitoes. K9 advantix ii. For the love of dog. Constipated . Trust number one doctor recommended dulcolax use dulcolax tablets for gentle overnight relief suppositories for relief in minutes and stool softeners for comfortable relief of hard stools. pelley Michael Morrell is our senior cbs contributor. Michael, if the four months since paris, authorities have been watching these neighborhoods in brussels. They have been raiding home, tapping phones. How did isis pull this off today . Scott, i think its a combination of two things. One, its a combination of how sophisticated these guys are. The investigative report showed the use of throwaway phone, sophisticated document forgery, the making of bombs in europe by bombmaking experts, the ability to move money around, the use of encrypted apps that Intelligence Services cant read, very sophisticated, right. Thats one reason. The other is the very large numbers of individuals were dealing with here. 5,000 people went from western europe to iraq and syria the fight. Some of them have died. Some of them are coming home in numbers huge. Put those two things together, its a very, very challenging problem. Drew pelley are you saying these guys are experts at what theyre doing . Theyre very good from my perspective, and they were trained in iraq and syria by pros. Pelley where are we now in the fight against isis . I think you have to look, scott,what they want to do, which is conduct attacks against us, and what we want to do, is stop them by degrading that capability. In the foreign. In the last four and a half months, scott, theyve had four victories, theyve brought down an airliner in the sinai, one of their affiliates. They conducted the attacks in paris, a directed attack. San bernardino, an inspired attack, and now brussels, either inspired or directed. Thats a pace of operations that al qaeda never dreamed of. Right. These guys are doing very well in doing what they want to do and were not degrading them. Pelley what in your view should be done in so, scott, i think there are two things we have to look at. Al qaeda went after symbolic targets on the far side of security. You had to get through scrutiny to bring down an airliner. These guys are going after soft targets on the near side of security. We have to push that security perimeter out. Number, two we need better intelligence on the defensive side. On the offensive side, i only know two ways to fundamentally degrade a terrorist organization. One is to remove rapidly the leadership from the battlefield and the other is to take their safe haven away. We have to pick up the pace on those two. Pelley Michael Morrell, former number two at the c. I. A. Michael, thank you so much. The f. B. I. Took immediate action today after the attacks. Well have that next. About what to avoid, where to go. And how to deal with my uc. To me, that was normal. Until i talked to my doctor. She told me that humira helps people like me get uc under control and keep it under control when certain well enough. Humira can lower your ability to fight infections, including tuberculosis. 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We know what it means to serve. Get an Auto Insurance quote and see why 92 of our members plan to stay for life. rebecca ive struggled with depression. I thought i needed cigarettes to cope. I was able to quit smoking. Now, i feel a lot better. announcer you can quit. For free help, call 1800quitnow. Pelley late today the federal government said there is no specific credible intelligence of any plots against the United States. But Homeland Security correspondent jeff pegues reports that Law Enforcement is very concerned about what it doesnt know. In brussels, the f. B. I. Stepped up surveillance of potential terrorism suspects in the United States. Diego rodriguez is an assistant director of the f. B. I. Were going to ramp up on all of our subjects here 24 7 surveillance and cover them just in the event that there is some type of connection. Reporter officials are concerned about the potential for isis sympathizers to plot attacks in the u. S. [explosion] there was a similar fear after the paris attacks in november. Frank cillufo is a former white house Counter Terrorism official. The concern is could there be copycats in the u. S. You always need to be worried about copycats because there is an old saying, terrorists are not innovators, theyre imitators. Reporter according to this report by