boston, thank you. >> and, you know, tahman just briefly touched on the investigation into those bombings. >> yeah, of particular interest this morning is what's left of that common pressure cooker. that's where abc's brian ross continues our coverage. >> reporter: this is what remains of the pressure cooker turned into a homemade bomb seen in this fbi crime lab photo obtained by abc news. it was hidden in a black backpack. the simple bombs were responsible for 12 seconds of horror. cell phone footage shot by a spectator between the two explosions. authorities are going through race day videos frame by frame. here the white smoke seen after the detonation indicates a bomb built with low velocity explosive mixtures, not the more powerful military grade. >> they may not have had the resources as we've seen in other bomb attacks, but they knew how to make the bomb go boom. >> reporter: but tuesday there was a new plea for help in identifying the bomber. >> any individual who expressed a desire to target the marathon, suspicious interest in researching how to create explosive devices, the noise of explosions in remote areas prior to yesterday, which may have been used as tests by those responsible for these acts. >> reporter: the efforts to learn who is behind the bombing often require great patience and persistence. it took three years and only after the discovery of a tiny electronic part that authorities learned who was behind the bomb that brought down pan am flight 103. the so-called unabomber was at large for some 17 years hiding out in the mountains of montana in a cabin before a relative finally turned him in. in oklahoma city authorities got lucky in a few days tracing the debris of the truck bomb and its axle to the rental firm and then to bomber timothy mcveigh. mike sullivan, the former head of the atf, the federal agency that investigates bombings, gave me insight tuesday near the boston crime scene. >> the smallest piece of evidence we would look at and simply walk over they would capture and say that's a treasure trove for them. >> reporter: even a little piece like that. >> yeah, critically important. you know, it could be the one piece that might tell them exactly how the device was detonated, and that might be the only piece that's left. >> reporter: brian ross, abc news, boston. so many families toughed by the tragedy in boston. we will have more on their stories later in this half hour and, of course, complete coverage coming up on "good morning america." and now we want to get to a brief check of the nation's weather. there will be clear skies from new england and the northeast. rain from the carolinas into the deep south. but violent storms stretch from texas all the way into the midwest, and then more snow from the northern plains and rockies. >> temperatures in colorado remain well below normal. low 80s across the southeast. 50s around the great lakes and seasonable readings up and down the east coast. coming up, it's happening right now, the funeral of margaret thatcher, and we're going live to london. back on the air, what american airlines is offering passengers from a computer glitch grounded its entire fleet in a live report. and a mother's wish for her two sons, both of them injured in boston. her story straight ahead. developing overnight, senator chuck schumer appeared on the senate floor at around 2:00 a.m. to officially file a bipartisan immigration reform bill. the legislation would secure borders, revamp legal immigration, boost workplace enforcement and put 11 million people in the u.s. illegally on the path to citizenship. and a scare on capitol hill. according to missouri senator claire mccaskill, investigators have identified a suspect who may have sent a suspicious letter to one of her colleagues. that letter was addressed to mississippi senator roger wicker. preliminary tests show the presence of the potentially lethal poison ricin. more extensive testing on that letter is now under way. travel nightmare for thousands of travelers after a computer glitch forced american airlines to ground its entire fleet. even though the problem has been fixed, more cancellations expected today. the latest from abc's preeti arla. >> reporter: american airlines hopes to get its flights off the ground today but still won't be running at full speed. the airline said it fixed a problem with its computer network that left tens of thousands stranded yesterday. still, there is a backlog after the airline grounded all of its planes. >> we're waiting to see what is happening. they say they'll make reservations for us in a hotel or get on a flight today, but we don't know. >> reporter: from dallas to chicago to miami, planes sat on the tarmac, and passengers waited in long lines. in all nearly 1,000 flights canceled and hundreds more delayed. >> the positive aspect is everybody is being very pleasant. the not so great aspect is we have no idea when we're going to get home. >> reporter: the computer glitch left ticket agents unable to access information and the airlines operation center had no way to update schedules or even track bags. a huge frustration for passengers. >> just trying to see when i'm going to get home, you know. i got my poor baby at home waiting for me. >> reporter: and a huge embarrassment for the nation's third largest airline, which is preparing to merge with us airways to become the world's biggest carrier. >> we're responsible for getting you to business meetings, vacations and to see your family and friends, and that's a responsibility we take very seriously, and we don't like to let you down. >> reporter: american offered to book passengers on other airlines so they could get to where they needed to go. they'll also offer refunds to stranded passengers. diana? >> all right, preeti arla in washington for us to morning. thank you. and now to london where security is extremely tight this morning for the funeral of former british prime minister margaret thatcher. abc's lama hasan joins us now on the phone from st. paul's cathedral. lama, what's the mood there this morning? >> reporter: yeah, good morning to you, diana. well, i would describe it as somber and symbolic. symbolic because this is a ceremonial funeral with full military honors normally reserved for senior members of the royal family like what we saw for princess diana and the queen mother 11 years ago. this has been awarded to honor britain's first female prime minister. now, the ceremony will be a solemn ceremony at st. paul's cathedral watched by 2300 guests. mourners from 170 countries including the queen and prince philip. this is the queen's first funeral of a prime minister since winston churchill's funeral in 1965. now, leading the u.s. delegation is james baker, george shultz, henry kissinger and dick cheney, and as you rightly said, security is tight. security offices have been on heightened alert in the wake of the boston bombings. attention has slightly switched from policing the protesters, who wanted to disrupt the procession when the coffin passed them by turning their backs to the coffin in a sign of disrespect while the security officers have now turned their attention to policing the whole area. 4,000 police officers are on duty fanning out across the city in an operation costing more than $5 million. diana. >> all right, lama hasan live for us in london this morning. thank you, lama. and coming up next on this wednesday, more from boston including the newtown connection, two towns, two tragedies. >> and lessons learned from the young victims. my family to eat breakfast, i need all the help i can get. that's why i like nutella. mom, what's the capital of west virginia? charleston. nutella is a delicious hazelnut spread my whole family loves. mom, have you seen my -- backpack? nutella goes great on whole-wheat toast or whole-grain waffles. and its great taste comes from a unique combination of simple ingredients like 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[ gasps ] until now. meet new covergirl clump crusher. big volume mascara with a brush designed to crush. now, i can load up my lashes to the extreme. 200% more volume. zero clumps. this is a lash addict's dream. new clump crusher from easy, breezy, beautiful, covergirl. do you really think brushing is enough to keep it clean? while brushing misses germs in 75% of your mouth, listerine® cleans virtually your entire mouth. so take your oral health to a whole new level. listerine®... power to your mouth™. check that out. not looking much like spring in denver. a doubleheader between the mets and rockies started two hours late thanks to a storm that dumped heavy snow across the region. players had a little fun before the crews descended on the field with the shovels. even the rockies owner and coaches pitched in. and it's not going to be a whole lot better with more snow falling on roads from denver all the way into the northern plains. storms threatened both commutes today across the nation's midsection, and it could be a slightly wet morning rush hour in the northeast. now if you're flying, airport delays are possible in dallas, kansas city, chicago, minneapolis and denver. all right. here are the latest headlines on the boston bomb investigation. the fbi has sent a bulletin to law enforcement agencies showing what appears to be a mangled partially exploded pressure cooker, and the shredded bag believed to have hidden one of the devices. >> investigators have recovered a partial circuit board that may have been used to trigger the bomb but the fbi says the range of suspects and motives remains wide open. president obama travels to boston tomorrow for a memorial service. and ahead of that service, the three victims killed in the blast being remembered this morning. abc's terry moran continues our coverage. >> reporter: a candlelight vigil in the tight-knit neighborhood of dorchester for one of their own, a beautiful gap-toothed 8-year-old boy named martin richard, killed at the finish line of the marathon just after getting some ice cream. there is so much love here. >> we're here for support and love. that's what we do. >> reporter: they are dorchester strong, and they came out for martin and for his family who are suffering so much. here a family facebook photo, his mother denise recovering now from severe head injuries, his 6-year-old sister jane who lost a leg, his brother henry and his father bill. what does this do for you to be here? >> if it happened to my family, i know they'd be here for me. >> respect. it's terrible, it's awful, especially for the mother and the daughter. it's awful. >> reporter: neighbors dropped off flowers at the martin home. the clock in the center of town was stopped at the moment he was killed, and at a park where he used to play, children scrawled "pray for martin." >> when they announced it, i was like is it this martin, and then when i saw the last name i was like, yeah, and i thought it was very sad. >> reporter: so we grieve for martin richard, and we learned another name, another of the dead of the boston marathon. >> we are heartbroken about krystle marie. >> reporter: krystle marie campbell was 29 years old. she was at the marathon cheering on her friend's boyfriend. she was a manager at jimmy's steak house. she took care of her sick grandmother, and her dad, william campbell, told us she was every father's dream. her mother patty spoke outside her home. >> she was always smiling. i couldn't ask for a better daughter. we can't believe this has happened. she was such a hard worker at everything she did. this doesn't make any sense. >> reporter: the third victim in the bombing, a chinese graduate student at boston university. her family in china has asked that her personal information not be disclosed. when the bombs went off, we knew evil was at work but so was good. it always is. >> but we also as a community and as a city can come together. >> reporter: even in darkness there is light. >> and that was our terry moran. among those recovering from severe injuries are two brothers and each of them lost a leg. 33-year-old j.p. norden and his younger brother paul were at the marathon cheering on a friend when those bombs hit. each one of them went to the hospital not knowing what had happened to the other. their mother spoke to "good morning america's" josh elliott. >> what were those moments like when you first saw your boys? >> terrible. i wish i could take their place for them. it's terrible. for all those people it's -- it's just like i want to wake up and have it not be real. >> and their sister described what it was like to have her brothers in two different hospitals. >> the first question they have asked, they just keep asking about each other. >> that makes me happy to know that they're not caring to know like one is worried about the other one and knows his leg is gone and just like heartbreaking to me. >> those brothers made it through surgery okay but face a long road to recovery. for runners from newtown, connecticut, the explosions brought back painful memories of their own town's tragedy. tom abrams wasn't far from the finish line when the bombs went off. he was running to raise money for victims of december's shooting at sandy hook elementary school. his wife watched the horror unfold on tv. >> i cried again just like i did on 12/14. what newtown is trying to do is spread the message that it's not just about newtown. it's about all of us working together to create a safe community, a safe country. my heart goes out to those injured, and my heart goes out to those families. >> people in newtown have vowed to reach out to the people of boston just like people across the country did for them in december. the bombings have only made runners and organizers more committed on carrying on the tradition of the boston marathon. asked if the race will go on next year, organizers replied with an emphatic yes. one local congressman predicted twice the crowd next year. the marathon dates back 117 years. and the london marathon is this weekend. runners and spectators will observe 30 seconds of silence in memory of the boston victims and will wear black ribbons. despite security concerns, prince harry still plans to attend. all right, up next what native bostonian mark wahlberg told jimmy kimmel he wants to do to his kids after the bombing. plus, showing respect. what the archrival new york yankees did for fans of the boston red sox. to do the things that i wanted. my doctor diagnosed it as fibromyalgia -- thought to be the result of over-active nerves that cause chronic, widespread pain. lyrica is believed to calm these nerves. i learned lyrica can provide significant relief from fibromyalgia pain. so now, i can do more of the things i enjoy. lyrica is not for everyone. it may cause serious allergic reactions or suicidal thoughts or actions. tell your doctor right away if you have these, new or worsening depression, or unusual changes in mood or behavior. or swelling, trouble breathing, rash, hives, blisters, changes in eyesight including blurry vision, muscle pain with fever, or tired feeling. common side effects are dizziness, sleepiness, weight gain and swelling of hands, legs and feet. don't drink alcohol while taking lyrica. don't drive or use machinery until you know how lyrica affects you. those who have had a drug or alcohol problem may be more likely to misuse lyrica. with less pain, i'm feeling better with lyrica. ask your doctor if lyrica is right for your fibromyalgia pain. yeah, you betcha, honey. ahh, you think so? [ female announcer ] some mornings you just can't eat at the table. eggo® wafflers are packed with flavors like brown sugar cinnamon roll, so you don't need syrup. eggo® wafflers. simply delicious™. neil diamond's "sweet caroline" there, fan favorite in boston's fenway park but last night played at yankee stadium to honor the victims of marathon attack and to salute boston's resilient spirit. diamond responded on twitter telling the yankees, "you scored a home run in my heart." massachusetts native mark wahlberg appeared on "jimmy kimmel live" last night expressing his grief and frustration over the boston bombing. wahlberg told kimmel he's grateful his family and friends were spared and that he's ready and willing to do what he can for the victims. >> we have some people that we know that were affected by it, and, you know, we just got to do everything that we can to help those families, and obviously we have to do everything we can to start protecting our women and children and people in our country. i just wanted to rush home today and hug my kids, and, you know, it's a crazy world that we're living in. >> wahlberg added a request that everyone pray for the victims. all right, and here is the cover of the new "sports illustrated," maybe the defining image of the boston marathon attack. three police officers and that 78-year-old runner just moments after the first bomb blast. bill iffrig got back on his feet and crossed that finish line. 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