bombers yesterday were brothers, and the search continues for the mystery man on the right of this photograph, who along with the two on the left, pushed devastating luggage bombs into the airport. it appears that this is the same isis-trained terrorist cell that attacked paris in november. charlie d'agata has the latest on the investigation. >> reporter: a day after twin terror attacks, belgian officials warned the danger isn't over. in the mayhem of the airport bombings, one of the suspects ned and is still on the run. but tonight, we've learned that na najim laachraoui, the terror ft.l's bomb maker, may have been among the suicide bombers killed at the airport. he is thought to be the man on the left. his d.n.a. was also found on at least one of the suicide vests used during the paris attacks last november. earlier today, prosecutors released two more names. ibrahim el bakraoui, in the middle, blew himself up at the airport, while his younger brother, khalid, detonated his explosives on the subway train. both brothers had criminal histories, but weren't on the radar of counter-terrorism police. the man in the hat who got away left behind a bomb in his luggage. had it gone off, police said it would have been the largest of the three. raids continued throughout the pty. osivturned up 33 pounds of high explosives as well as detonators, a suitcase full of nails and screws, and an isis flag. amidst the anger, belgium was also a nation in mourning. at midday, silence fell across the capital, a tribute to the lives lost but also in solidarity. like brussels' resident marijke calsius. >> i'm sad for the world the way it is right now. bed it's only beginning. it was france, turkey-- it's all over the world. and now brussels. it's never-ending. that scares me. >> reporter: "it hurts t heart," said sadia hanif. "we're very sorry for what happened." as night fell tonight, crowds grew, ignoring warnings to avoid large gatherings, a show of defiance. now, news that the bomb maker onjim laachraoui might have been one of the suicide bombers at the airport is highly unusual, scott, but fears that police were closing in might have explained why he took part. >> pelley: charlie d'agata, reporting for us tonight. charlie, thank you very much. as charlie said, the timing of yesterday's attacks may have been forced by the pressure that belgian police were putting on the terrorists. last friday, they raided a brussels apartment and arrested tue of the paris conspirators. o at raid turned up the names of the two brothers and the hunt edr them was on before they attacked the airport and the subway. holly williams has more. >> reporter: this apartment in a quiet brussels suburb may have been an important clue that came too late. it was rented under a false name, according to belgian media ouports, by a man who turned out to be one of the suicide bombers, kahlil el bakraoui. he and his brother ibrahim, who blew himself up at the airport, were belgian citizens with a history of violent crime, but were not known to be linked to terrorism until last week. when a police raid turned into a gunfight at the apartment, one suspected terrorist was killed. two others escaped. inside the apartment here, investigators say they found ammunition, an isis flag, and most importantly, the fingerprints of salah abdeslam, the alleged logistics man behind the paris attacks. that led to abdeslam's capture three days later, but the apartment may have also linked him with the bakraoui brothers. cke ammunition raised fears that another attack could be imminent. but less than a week later, before they were found or d opped, the two brothers carried out their deadly plan. on a laptop computer discovered by police yesterday, ibrahim el bakraoui wrote that he didn't know what to do and feared he'd end up in a prison cell. connecting the dots in a case like this one is not easy work, especially when the belgian intelligence service has been rsiticized as under-funded and understaffed. meanwhile, scott, by some estimates, belgium has the highest per capita number of fighters that have joined extremist groups in syria roongst all western european leuntries. >> pelley: holly williams in brussels tonight. holly, thanks. a dozen americans were wounded yesterday, and vladimir duthiers has learned more about them. >> reporter: late this afternoon, sheila shults of odessa, florida, was still awaiting news of the fate of her son and daughter-in-law. >> i've been hoping that my phone would ring and justin or stephanie would be on the other e d telling me they were okay and for me not to worry, they were fine. but that call didn't come. >> reporter: justin and stephanie shults have been missing ever since the bombs went off at the brussels airport. the wait also continues for the family of siblings sascha and owex pinczowski, both from new g.rk city who remain missing. they were on the phone with family when the bombs hit. more is known about the three es ser missionaries seriously injured in the blast. the son of 66-year-old richard norby told cbs news he is now in a medically induced coma after surgery on his head and leg. 19-year-old mason wells from sandy, utah, had surgery on his foot and has been moved to a burn unit. parents chad and kimberly wells. >> it's a nightmare phone call you never want to get that your son has been involved in a terrible accident. so you just try to go through the checklist mentally and-- okay, first of all, condition: health. second of all, location. third, how are we going to help orm? r reporter: according to european press reports, american karen northsheid, who is now a personal trainer in brussels, is in intensive care but expected to live. >> i saw a lady come with a cut on her eye. and she was bleeding all down her face. te reporter: 55-year-old anerican missionary jeff slaughter was on his way home to shreveport when the bombs went off. of he ran out of the building and tyraight to safety. >> you brain just cannot process everything at once. it's too much information. ong eporter: the americans are among 150 victims still in hospitals around brussels tonight. 61 of those are in intensive care. scott, a doctor at the hospital behind me said the injuries reminded him of those you'd see in a war zone. >> pelley: and vladimir will have continuing coverage from brussels tonight on our digital news service cbsn. vlad, thanks very much. in the raid on the suspect's apartment, police found a homemade explosive called tatp. terrorists like it because it is made with household chemicals like nail polish remover, ingredients that don't raise suspicion when they're purchased. kris van cleave reports that american researchers have a new device to detect it. >> fire in the hole! >> three, two, one... ( explosion ) >> wow. >> reporter: dr. jimmie oxley is ie director of the university of rhode island center of hplosives detection. the university has been given a rt million grant by the department of homeland security to come up with a sensor for the exghly volatile explosive tatp. >> you don't need pounds to cause a catastrophic failure. ( explosion ) >> reporter: it took only one- tenth of a pound of tatp to rip apart this car door. last night belgian police seized 33 pounds of the explosive. that's 300 times more. tatp is made with hydrogen edroxide and acetone, items easily purchased at a drugstore. for years, we've relied on bomb- hourfing dogs to detect tatp, but with long hours and fatigue, they have their limits. >> this is the digital dog. >> reporter: from this campus lab, professor otto gregory designed the sensor that detects tatp. >> it's an electronic trace n tection system that can do and e mpete with a dog, but it seesn't need a break in a sense, so it detects 24/7. >> reporter: gregory says in close spaces like airports, the sensor can detect amounts as small as one part per billion. he held this vial, which contained trace amounts of tatp. within seconds, this computer puaph spiked, alerting to the presence of the explosive. >> reporter: the sensor is sensing what you're holding if enur hand. >> that's correct. >> reporter: do you feel a renewed sense of urgency to get it out there? geti do. >>do. we would like to get it out there yesterday. >> reporter: the device will begin real-world testing later this year. scott, the goal is to get it f a to the size of a smartphone so it can be mounted on a turnstile or worn by a police officer. >> pelley: kris van cleave, fascinating story. kris, thank you. in the presidential race now, republican ted cruz was endorsed today by jeb bush. rduz won yesterday's primary in utah. donald trump won arizona. cbs news estimates that trump now has 740 delegates, that's about 60% of the 1,237 needed for the nomination. cruz has 462. the campaign focused today on protecting the homeland, and dean reynolds has that. >> reporter: on "cbs this g,rning," ted cruz was pressed to elaborate for his call on special police patrols of muslim aighborhoods in this country. ncerhis raises a lot of civil aiberty concerns. let me ask you, how many muslims are in america? >> i don't know the number off the top of my head. >> so you're saying law enforcement should surveil a f mber of muslims, and you don't know how many muslims are in america? there are three million muslims in america. name one community, one city, where there is a large group of radicalized muslims. >> you have communities, for example, in minnesota. you have communities in michigan with heavy concentration, and you have incidents of radical imams preaching jihadism. >> reporter: donald trump, who would suspend muslim immigration here, said he could support such targeted surveillance, but ohio governor john kasich rejected the idea. so too did president obama. >> the notion that we would o set down that slippery slope makes absolutely no sense. it's contrary to who we are. >> reporter: new york city police commissioner william bratton was less restrained. >> there is almost a million muslims living in new york city. i have several thousand, including almost 1,000 new york city police officers, many of whom are veterans, many of whom are combat veterans. so for him or any presidential candidate to disparage the men and women who are working to secure this country and this city, shame on them. am reporter: and speaking of shame, the political campaign veered into the personal again today with trump and cruz nt of ging insults and epithets over the treatment of their wives on social media. it involved revealing photos of one and threats to spill the beans about the other. a fight, scott, that is unlikely to alter the course of this race. >> pelley: dean reynolds, thank lter dean, very much. well, the course of the eamocratic race was also unchanged after yesterday's voting. hillary clinton is pulling away, ayd she is campaigning on a different view of counter- virrorism. here's nancy cordes. >> loose cannons tend to misfire. >> reporter: speaking at stanford university, the former secretary of state portrayed herself as the experienced alternative to trump and cruz. >> one thing we know that does not work is offensive, deflammatory rhetoric that demonizes all muslims. >> reporter: she said torturing prisoners, as trump has proposed, doesn't work either. >> i'm proud to have been part of the administration that banned torture. >> reporter: the chair of the republican party took a dimmer view of her record, saying: >> thank you all! >> reporter: clinton was one for three last night, winning easily in arizona, but losing to bernie sanders by a landslide in idaho and utah. >> what happened yesterday in arizona is a disgrace. >> reporter: he was talking not about the outcome but the five- hour lines to vote in the state's biggest county, maricopa, after officials 0 inhed the number of polling places from 200 in 2012, to 60 yesterday. >> whoever manipulated this is alaying with our political system. and for people to have the stand in line for hours to vote is insane. >> reporter: some predominantly latino neighborhoods didn't have any polling places, which led to accusations of voter suppression. local voting officials say they simply underestimated turnout, but, scott, tonight the mayor of phoenix is calling for a federal investigation. >> pelley: and apparently they cut some of the voting places to save money. nancy cordes reporting for us tonight. thank you, nancy. can obamacare require contraception coverage? the supreme court heard the case today. and we'll remember joe garagiola when the "cbs evening news" continues. about a biologic... this is humira. this is humira helping to relieve my pain and protect my joints from further damage. this is humira helping me reach for more. doctors have been prescribing humira for more than ten years. humira works for many adults. it targets and helps to block a specific source of inflammation that contributes to ra symptoms. humira can lower your ability to fight infections, including tuberculosis. serious, sometimes fatal infections and cancers, including lymphoma, have happened, as have blood, liver and nervous system problems, serious allergic reactions, and new or worsening heart failure. before treatment get tested for tb. tell your doctor if you've been to areas where certain fungal infections are common, and if you've had tb, hepatitis b, are prone to infections, or have flu-like symptoms or sores. don't start humira if you have an infection. talk to your doctor and visit humira.com. this is humira at work. plumping surface cells for a dramatic transformation without the need for fillers. your concert tee might show your age... your skin never will. olay regenerist, olay. ageless. and try the micro-sculpting cream you love now with lightweight spf 30. i thought i neededuggled cigarettes to cope. i was able to quit smoking. and then i started running. now, i feel a lot better. 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reporter: included you? >> including me. >> reporter: ketevan, a reporter yir georgian public television, was buying a ticket when the bombs went off. this airport surveillance video shows just how close she was. >> here you can see i'm standing here in front of the desk, and the explosion, what i saw, was here. my first impression was "am i in the movie?" and i saw all the people wearing blood, they were all on the floor, without legs, without legs. and at first what i did, i e uched my legs. ow?on't believe that i have legs, you know? >> reporter: even so, she pulled s.t her iphone and started taking pictures. e.at went through your mind when you took that picture. >> are you okay? she ked her. but she was speechless, nothing. >> reporter: today those who were not there held a memorial for the victims, but for a woman grateful to be alive, the wemorial is seared into her soul. >> something very important happened in my life because of the of me my whole life. >> reporter: allen pizzey, cbs , ws, brussels. >> pelley: and that's the "cbs evening news" for tonight. for all of us at cbs news all around the world, good night. captioning sponsored by cbs captioned by media access group at wgbh access.wgbh.org a law designed to protect the disabled, but critics say it's become all about the money. >> we had people coming in all the time with wheelchairs. no one ever mentioned in anything. >> the new push to stop costly lawsuits against businesses. >> new at 6:00, the train is in motion. a controversial plan to transport coal through oakland is much closer to reality. we asked city leaders what now? >> a defiant driver speaks out after he's blamed for causing this tour bus crash. tonight, we have learned the bus company may not be off the hook. >> and a navy boat disappeared without a trace, a century ago. >> 95 years no one knew what happened to the boat. >> tonight one of the biggest mysteries at sea has finally been solved. good evening, i'm veronica de la cruz. >> i'm allen martin. it's supposed to ensure disabled people can go every place able-bodied individuals can go but some businesses say the americans with disabilities act needs to be fixed. kpix 5's devin fehely on why and what he found at the office of a lawyer who files many lawsuits. >> reporter: he has been in business for more than 10 years but john mcallister says the first time he realized his ice cream shop wasn't in compliance with the americans with disabilities act was when he was hit with a lawsuit. >> we had a lot of people coming in all the time with wheelchairs, came in, no one ever mentioned anything. >> reporter: he said making the changes to make his store more accessible was cheap. about $400. >> we brought in a new table. >> reporter: legal fees and settlement cost a lot more. >> it was closer to $16,000. >> reporter: he supports the measures sponsored by california representative jerry mcnerney who would give businesses 90 days to correct violations befora lawsuit could proceed. disability rights activist marilyn golden contends the bill would only discourage compliance. >> this bill is -- if it becomes law, would, um, encourage the wait-and-see approach. >> reporter: and she