grenades, and a short time later he was under arrest. police radio relayed the word. >> subject in custody. subject in custody. >> reporter: boston transit police actually put the handcuffs on his wrists, taking on that duty to honor richard donahue, the transit police officer wounded thursday night in a shoot-out with the tsarnaev brothers. among questions so far unanswered, where were the bombs built, and did the bombers test explosives somewhere outside of town, did they have help. so far investigators say the answer seems to be no. where did they get their guns? investigators are working to trace that now. what were they doing after the bombings? dzhokhar tsarnaev's classmates say he returned tuesday to the dartmouth campus where he was a student. and what was his brother, tamerlan, doing last january when he visited his father in dagestan? did that trip have anything to do with the bombing or his radicalization? as for the boston marathon bombing itself, those who

have seen a still unreleased surveillance video acquired by the fbi say it shows dzhokhar tsarnaev removing his backpack at the spot where the second bomb was placed and acting very differently from those around him when the first bomb went off. >> it does seem to be pretty clear that this suspect took the backpack off, put it down, did not react when the first explosion went off and then moved away from the backpack in time for the second explosion. so pretty clear about his involvement and pretty chilling, frankly, as it was described to me. >> and this one other note -- police say that the brothers carjacked an suv thursday night and held the car's owner at gunpoint. he tells nbc news tonight that he escaped when they stopped at a gas station. he described them as "brutal and cautious." he asked that we not identify

him, and he declined an on-camera interview, lester. >> pete, it is our understanding criminal charges are being prepared as we speak but there are some on capitol hill who want to ramp this up to an act of war. what other options are there in terms of charging this young man? >> well, he's going to be charged in civilian court. and even the republicans on -- in congress say that they understand that. what they want the government to do is declare him an enemy combatant simply for the purpose of questioning and then turning him back over to civilian authorities for the trial. but tonight the justice department says that's not going to happen. >> all right, pete williams tonight, thank you. as authorities search for answers, they are turning more of their attention to a trip the older brother made last year to the russian republics of chechnya and dagestan, both mainly muslim, both with militant separatist movements. tonight nbc's adrian mong is in dagestan in the neighborhood where some of the suspect's family lives. >> reporter: a long way from boston in this remote mountainous city in dagestan in the northern caucasus, relatives and friends of the suspected

bombers are in shock over the news that two of their own may have been responsible for the marathon bombings. "i don't believe it but only allah knows," says an uncle of the brothers. tamerlan tsarnaev visited him when he traveled to dagestan last year. in the neighborhood where tamerlan and dzhokhar's father lives, the same sentiment. neighbors here on the street tell us they have a hard time believing what happened because they say the suspect's father is a good man. but the neighbors also say they haven't met the sons. dagestan is the russian federation's oldest, largest and most ethnically diverse islamic republic. its population of almost 3 million, predominantly muslim, has in recent years come under increased scrutiny by russian authorities. "they started closing our mosques and taking away our books," says this civil rights activist. and dagestan has attracted rebels from neighboring chechnya, hoping to spread a a pan-islamic separatist

movement across the north caucasus region. investigators are still looking into whether tamerlan had any connection to militants in either dagestan or chechnya. adrian mong, nbc news, dagestan. back in boston, this was a day of reflection as the dead and wounded were remembered, and the city began to reopen after the horror of the past week. nbc's ron allen is there for us tonight. ♪ >> reporter: boston's heart burst out in song today on the streets near where so many victims of the marathon bombing were wounded last week. ♪ i'm going to let it shine >> evil will always happen in this world, yet we can combat it with good, we can combat it with love. >> reporter: worshippers who couldn't get to churches inside the cordoned off crime scene attended services outside. ♪ let peace begin with me >> reporter: at the cathedral of the holy cross, powerful portraits stood before a congregation filled with heavy hearts. pictures of those killed by the bomb blasts. krystle campbell, 29, lingzi lu,

23 and martin richard, just 8. and police officer sean collier, 26, murdered allegedly by the suspects. at m.i.t. today a tribute where collier died on campus. >> i see a young man with incredible potential. i think the sky was the limit with him, and i think that in the future we would have heard a lot from him. m.i.t. is a real special place, and it is the real deal, and they deserve the reputation they have is deserved beyond deserved. but this is a whole other side that i'm starting to see. >> reporter: more than 50 people wounded in the blast remain hospitalized, including a 7-year-old girl in critical condition, and transit officer richard donahue, ironically a close friend of officer collier, gravely wounded during the chase for the two suspects. >> he works for the transit, and i'll always tell him you're never going to see any action because you're on the subway. but, you know, there he is jumping into the midst of a gunfight in watertown and

making transit very proud. >> reporter: at the university of massachusetts, where suspect dzhokhar tsarnaev was enrolled, campus reopened with stunned students reacting to finding out an alleged bomber was in their midst. >> after what i saw, it was like a small army here, i assume that we're good to go. i'm glad they took all the precautions they did. >> this is a line into center field. >> reporter: through it all, boston strives to return to normal. the red sox played a doubleheader to make up a game canceled because of friday's manhunt. still, it's hard to ignore the powerful attraction and emotions at the memorial near the marathon's finish line where people come from near and far. some bringing friends who have a special touch. >> how old are you? >> 3. he'll be 4 in june. >> it's been almost a week. still a lot of feeling. >> oh, absolutely. absolutely. i mean, that's why i came up today. it is a beautiful day, and i thought what better way to spend it than to come to boston. >> reporter: late today

officials here said it is still going to take a while to reopen the center of the city behind me because that's still a huge crime scene, and they've asked everyone to observe a moment of silence tomorrow at 2:50 p.m., exactly one week after the bombs exploded, and then church bells will ring signaling the way forward. lester? >> ron allen tonight in boston, thanks. and last night in boston, it was a spectacular spring day today in london as that city held its marathon under heightened security and in solidarity with the people of boston. nbc's duncan golestani was there. >> reporter: hundreds of thousands lined up just as the boston runners did six days ago. that's when the whistle blew london's competitors stood still for 30 seconds wearing black ribbons, they joined together in silence to remember those who died and those injured far away. on this sunny spring day the shadow of the boston attacks could be felt here. from the 40% increase in police

protection to extra bomb-sniffing dogs checking bags. this was about re-assurance and it worked. >> well, they're here. if anybody's afraid, they wouldn't be here, would they? >> reporter: keeping a close eye, the hundreds of thousands of surveillance cameras installed as a result of past terror attacks, including the 2005 bombings, which killed 52 people. londoners are known for their resilience. despite the bombings in boston, the crowds here are defiant. they have come out in their hundreds of thousands determined to cheer on the runners. london's embrace was especially noticed by its competitors. in boston tatiana mcfadden won the women's wheelchair race. >> tatiana mcfadden. >> reporter: in london, a second victory yet still bittersweet. >> it's about hope, you know, and it's about bringing hope to the people back in boston, and so that's what the race was about today, and i really dedicate the race to boston. >> reporter: the messages of

goodwill work in both ways, from prince harry poised at the finish -- >> the way boston's dealt with it has been absolutely remarkable. >> reporter: to boston's transit police "we hope you and you will the runners have a great day." two cities with one message, we remain defiant. duncan golestani, nbc news, london. when "nightly news" continues on this sunday, rising floodwaters in the midwest where many are still bracing for the worst. and later a deadly weekend in ski country. we'll go to colorado where the avalanche struck.

states of emergency in the midwest tonight as dozens of rivers have overflowed their banks triggering deadly flooding. nbc's john yang has the latest from clarksville, missouri. john, good evening. >> reporter: good evening, lester.

so far, this round of the river versus man is going to the residents of clarksville, missouri. four days of furious sandbagging have kept the water from inundating downtown. >> okay. ready? >> reporter: trish connelly had planned to open a new fine arts gallery in clarksville's historic downtown this weekend. instead, she's been sandbagging to try to save it. >> everybody's pulling and helping. we could just still use more help. >> reporter: this town 75 miles north of st. louis has flooded at least 4 times in the last 18 years. this year, it's come early. the high water forced the army corps of engineers to close locks and halt traffic. two bridges were closed for several hours after more than 100 barges broke loose saturday night south of st. louis. it's a far cry from just a few months ago when drought conditions threatened to bring river traffic to a standstill. rivers are rising fast across a huge swath of the midwest, a

result of last week's storms dumping a month's worth of rain in just a few hours. it triggered widespread flash flooding and sinkholes in chicago and caused dozens of rivers to swell. evacuations are under way, roads closed as hundreds of acres of farmland are swallowed by water. at least three deaths are blamed on the floodwaters. in central indiana, today, authorities found the body of a man swept away by rising water. >> 911 called, and they said water picked his truck up. last words he said call bob baker, which is me. >> reporter: in lowell, michigan, near grand rapids, record floodwaters damaged hundreds of homes and dozens of businesses. back in clarksville standing on the deck of his house, douglas getten says he feels like he's on the deck of a ship. >> when the river is low it is a beauty. when it's high, it's a beast. >> reporter: tonight the town's holding its breath anxiously waiting to see if the sandbags hold, and they know this is only the beginning. >> we're not out of the woods.

if we have rain up north or that quick snow melt, we're going to see higher levels yet. >> reporter: already major flooding forecast for later this week from northern iowa to st. louis. lester? >> anxious days there, john, thanks. four days after that huge explosion at a fertilizer plant in central texas, everyone is accounted for tonight with 14 people dead and 200 injured. more residents returned home today, but the area closest to the plant is still off-limits. nbc's gabe gutierrez has the latest. >> reporter: new video of the damage in west, texas, after a fertilizer facility exploded in a blinding fireball. for the first time we see an apartment complex ripped open. chunks of concrete tossed hundreds of yards. a school heavily damaged, and this nursing home shattered. today investigators said they found the origin of the

explosion but won't say where or what triggered it, and they still aren't sure what caused wednesday's initial fire. >> we know that there was an initial fire and then an explosion. we do not have a time line. >> reporter: local authorities say everyone is accounted for, and they don't expect to find any more bodies. 14 people were killed, including buck utmore. >> i mean, we are such a close family. it is just such a big hole. just such a big hole in it now. >> just move forward and get in line. >> reporter: today police check points more residents were allowed back into their homes but the area closest to the plant is still off-limits. >> my daughter's house is caved in, but we'd at least like to be able to get in and start cleaning up and salvaging what can be salvaged. >> we're going to have to have church outside. >> reporter: on this somber sunday in texas, a displaced congregation attended church outside knowing their town would never be the same. gabe gutierrez, nbc news, west, texas. when we come back here tonight, what caused a deadly avalanche in colorado.

it happened in an instant this weekend, a huge avalanche that came crashing down on a group of snowboarders in colorado. five of them were killed, a tragic reminder that the thrill of going beyond the boundaries can come at a tremendous cost. we get the story tonight from nbc's leanne gregg. >> reporter: a day after five snowboarders were killed in a massive back country avalanche on loveland pass, thrill seekers returned. >> the adrenaline rush. that's why i'm here. >> back country skiing is amazing. it is fantastic. but everyone has to be cognizant of the risk at all times. >> reporter: they were not far from where the 600-foot-wide and 8-foot-deep avalanche swept up six snowboarders. only one survived. he freed himself and called for help. when rescuers arrived it was too late for the others. >> they were buried in very hard, heavy debris, so they either sustained injuries or they died from suffocating in the debris pile. >> reporter: all six men in their 30s were expert riders.

among those who perished, ian lamphere, trained as a heli ski guide in alaska. rick goccle, who a friend called one of the most educated back country guides in the world and joe timlin, who is quoted as saying snowboarding was his life. they were all well equipped with proper safety gear. >> just because you have all the rescue equipment, it doesn't prevent the avalanches. >> reporter: this helmet video of a skier caught in an avalanche shows the horror of being trapped under a mountain of snow. he was able to create an air pocket and a quick response from friends saved his life. saturday's avalanche was the deadliest in colorado in more than 50 years. this season nationwide 24 people have died in avalanches. 11 in colorado. heavy spring snow, more than three feet in less than two weeks, has caused volatile conditions. >> if you go to the wrong place, the outcome is tragic. >> reporter: a somber call for caution as the ski and snowboard community mourns for five of their own.

leanne gregg, nbc news, loveland pass, colorado. in china, rescuers are still trying to save people who may have been trapped in the country's worst earthquake in three years. officials say the death toll has risen to 208 with almost 12,000 injured. 1,000 of them seriously. the 6.6 quake happened yesterday in sichuan province in southwestern china. and as the civil war in syria rages on, the u.s. said today it will double the aid to the opposition. secretary of state john kerry made the announcement at a meeting in turkey saying the u.s. will give the syrian rebels $123 million in new assistance. some will go to additional n nonlethal supplies for the military wing of the rebel coalition trying to overthrow the assad regime. an american financier announced today he is creating a $300 million scholarship program for studying in china. stephen schwarzman, head of the blackstone group,

said the money will finance a masters program at a university in beijing. 200 students from the u.s. and around the world will attend each year. schwarzman will donate $100 million from his personal fortune. up next here tonight -- what they mean by boston strong. ♪ sweet caroline

finally tonight, a city living up to its new rallying cry -- boston strong. it was seen and heard all over boston today as the city emerged from one of its darkest

chapters. nbc's katy tur has more tonight. >> reporter: sunday in boston, and faneuil hall is filled with music. ♪ newbury street lined with shoppers and boston common only two days ago deserted is now full of children. >> it felt like an infusion of 60,000 people came in a matter of -- overnight. >> reporter: the city that started the american revolution proving its strength by simply moving forward. >> you don't mess with boston. it's a very, very resilient town. people here -- life will go on. >> reporter: judy and susan, both nurses at brigham and women's, came to the edge of boylston street for the first time since the tragedy to lay flowers. >> i know what the injuries were and i just needed to come down and see it for myself. >> reporter: in boston the big signs of support have been just as important as the little ones. free hugs on boylston street. >> yeah, boston -- woo!

>> reporter: memorials both temporary and permanent. >> see how great the community is getting behind you girls? >> reporter: simple gestures surpassing the wildest expectations. bridget, lauren, sierra and mary baked brownies well past their bedtimes to raise money for people they've never met. the family of 8-year-old martin richard. they hoped to make $100. so far they raised more than $5,000. >> we wanted to give cookies to all boston police. >> reporter: today they delivered cookies to boston's finest. today they delivered cookies to boston's finest. >> it is great that they helped and i really wanted to thank them. >> reporter: boston strong, wicked strong, we are one boston. >> i feel like a firefighter i'm getting so much love. all right? >> this is boston. my home. i'll never turn my back on it, you know? >> reporter: katy tur, nbc news, boston. that's nbc news "nightly news" for this sunday. brian williams will be here tomorrow. i'm lester holt reporting from new york. and for all of us here at nbc news, goodnight. i knew there were a lot of tech jobs available out there.

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it's hot for this time of year but certainly not unbearable. i assume most folks are enjoying it out there. >> reporter: they are enjoying it. we're all enjoying it out here. we did a nonscientific survey. most people say it's not scorching hot, it's actually quite comfortable. everyone is out here just soaking up the rays and enjoying it. but spring certainly does feel more like summer today. families are taking advantage of mother nature's grace. in downtown an jose there's no shortage of kids enjoying the fun in the water fountains out there. parents say it's a win/win. plenty of shade for them and water for the kids. >> it's hot. >> did you enjoy it out here? >> yeah. i enjoy getting wet. >> this is fun for them. it's fun, it's free. and it's keeping them nice and cool. >> pretty nice. pretty good. >> reporter: surprising for an april day? >> yes. >> reporter: we saw a lot of people finding shelter from the sun with big water bottles. two important things given the heat, another one to keep in mind today, sunscreen. lots of moms shaking their kids

around, trying to put sunscreen on them. >> thanks a lot. hot in the east bay as well. how about nearly 90 degrees in sinole this afternoon. spring heat wave apparently just getting started. anthony, looks like the record is going to be coming tumbling down tomorrow. >> if you've lived in the bay area long enough you'll note back in 2009, that's when we saw our last heat wave like this in april. we're looking at smashing really widespread records across the board tomorrow. in fact, today the hottest spot, gilroy at 89. livermore 89 as well. san jose, 86. everybody else very warm. mid to upper 80s across the board. santa teresa another warm spot at 90. tomorrow will get a little warmer. san jose will actually be at 9 tomorr -- 89 tomorrow. that will tie an old record 1998. 2009 was a year we had many records in april broken. also