good evening. it appears the militant group known as isis is about to face a big setback, losing control of tikrit just 90 miles north of baghdad. the battle raged for days between isis and iraqi forces. even some americans are on the ground including former military, trying to deliver a blow to the group which still controls huge parts of iraq and syria. nbc's bill nealy is in irbil tonight and starts us off. bill, good evening. >> reporter: good evening, carl. we've witnessed the fight against isis firsthand today. we've been with kurdish troops who are pushing isis back, and they're being helped by american volunteers. further signs who say iraqi militias who are taking on isis and iraqi government source told nbc news, isis is losing tikrit. isis is under heavy fire. rockets and mortars raining down on isis positions. these are iraqi militias, armed and backed by iran and spearheading the attack on tikrit. isis is dug into the city center and surrounded. the militias are already celebrating, but they won't move in until they get reinforcements. isis has booby-trapped buildings and roads. iraq's defense minister is predicting victory, and isis is clearly being pushed back on many fronts. kurdish troops are making gains. they took us to their front line with isis. from sandbag positions, we saw isis flags flying over two villages the kurds are attacking. there's been sporadic firing from isis positions here in the last few minutes. but there's no doubt that the momentum of this war is against isis here and for now. but the history of war in this part of iraq shows that can change and change quickly. >> i just get a boom, and i duck down, had glass go all over me. >> reporter: some americans have joined the fight against isis. micky came from colorado. not as an official u.s. adviser, but as a lone volunteer. >> i'm just here to help get rid of isis, to hit them where it hurts, in the root. >> is that what you're doing? >> that's what we're doing. there are people being raped, beheaded, enslaved, executed, thrown off of buildings. i'm not cool with that. >> reporter: jeremy woodart from mississippi is a retired u.s. soldier who served in iraq. he's back, another volunteer. how is it as an american to be fighting isis? >> it's something that needs to be done. because isis, they're a cancer to the world. if it doesn't stop here, it's going to keep on spreading. >> reporter: they claim more american volunteers are coming to join them, as the battle for saddam hussein's hometown reaches a decisive moment. now, those americans insist they have not been sent here by the u.s. government which has pledged no combat troops here. they say they're not mercenaries because they're not being paid. and they're not terrorists, certainly, they say isis are the terrorists who should be confronted here before they threaten the homeland. back to you, carl. >> bill nealy tonight, our thanks to you. incredible video of the little girl saved from the wreckage of a car that crashed into that frigid utah river. we're now seeing the rescue as it unfolded through the eyes of first responders as they frantically tried to save the life of lily grossbeck. here's nbc's halle jackson. >> reporter: it's a heart-stopping look at the nine minutes that saved baby lily's life. after she spent 14 hours upside down in a half submerged car. with no hesitation, first responders raced to the wreck, splashing into the icy river. >> get down here and we are going to flip it. >> reporter: on the body camera video, you realize the 18-month-old is inside. >> oh, god, there's a baby. >> reporter: along with her mother, who police say died when the car crashed. straining to get the baby out, they do. >> pass her up! pass her up! pass her up! go, go, go! >> reporter: rescuers moving fast, breathing hard. >> come on, baby. >> reporter: she's in trouble, and they know it. >> she's definitely hypothermic. she's freezing. >> reporter: they sprint to the ambulance where they try to get her blood circulating. >> come on, sweetie. >> reporter: wrapping her in a blanket, performing cpr. >> we're almost there. are you getting a pulse? >> reporter: finally they reach the hospital. >> straight in! we've been doing cpr on here. >> reporter: the video ends with lily grossbeck in the care of the doctors who helped save her life. >> underwater, yes. >> reporter: it's a breathtaking first-person perspective from the responders who jumped into action. >> everybody knew what they had to do. everybody was in the right position. everything happened just right. >> reporter: baby lily's story has captivated the country. her recovery and her return to her family, safe and healthy. >> i'm just really blessed, and i'm just glad to have my daughter here with me. i'm overwhelmed with joy right now. she's just a miracle to me. >> reporter: from start to finish, an incredible story of heroism and hope. halle jackson, nbc news, los angeles. tonight we're learning more about the damage from one of the pacific ocean's most powerful storms ever. cyclone pam has brought casualties and damage with the brunt of the impact felt by the tiny nation of vanuatu just east of australia. kelly kobaya has our report. >> reporter: the first images from the battered south pacific islands of vanuatu, homes ripped apart, trees shredded, sailboats shoved ashore. the island slammed by 168-mile-an-hour winds. >> winds were too strong. glass, windows were smashed. >> reporter: the united nations children's agency said half the population was affected by cyclone pam. more than 100,000 people, including 54,000 children. there are unconfirmed reports of remote villages wiped out and dozens dead. >> the wind was howling through my bedroom. i'm in the bathroom, with my bed against the door. >> reporter: unicef alice clemmons recorded this while riding out the storm. >> i'm just holding on for dear life here. this isn't fun. all i can do during this is think about people who have absolutely no shelter. this is going to be a horrific humanitarian disaster. we need your help. >> reporter: the president, braced for the worst, is already asking other countries for aid. >> i'm speaking with you today with a heart that is so heavy. >> reporter: this image from nasa was taken just before the category 5 storm reached the capital of port villa. the pacific island nation was a vulnerable target, with homes made of wood and tin and few places strong enough to survive the storm. with power out and phone lines down, the full extent of the damage is not yet clear. but relief agencies are preparing for a major rescue operation. kelly kobaya, nbc news, london. thousands of people have been evacuated in chile due to an out-of-control forest fire. frantic residents scrambled to collect their belongings as the blaze advanced to the port city. some 4,500 people have already been evacuated from the area and that number could rise to as many as 16,000. in this country, for many this week's rising temperatures have been a welcome relief, but thanks to all that record cold and snow, the warmer weather has also caused a major problem -- flooding. here's nbc's stephanie gosk. >> reporter: what happens when you take all that ice and then add all this rain? rivers can't handle the pressure. in vermillion, ohio, the water is spilling over the banks and it keeps rising. the high waters closing roads and invading homes. >> it came inside my house, about three feet in my house, destroyed everything. >> reporter: the peak is expected tomorrow morning when the river could reach six feet above flood stage. >> i'm terrified. yeah, i am pretty scared. >> reporter: all along major rivers in the eastern third of the u.s., from upstate new york, to louisiana, there are flood alerts. the region experienced record-breaking cold, and now must deal with a potentially dangerous thaw. >> we haven't seen things this bad in a very long time. >> reporter: river ice can be a formidable enemy. as the temperatures warm, the ice breaks and large chunks can easily create jams. the water has no place to go, but up and over its banks. when the jam breaks free, ice on the move can be destructive. >> the biggest concerns are for the businesses and the homes directly along the ohio river. >> reporter: so far this year, ohio is feeling the brunt of the thaw. the bitter cold may be over, but the winter woes won't let go. stephanie gosk, nbc news, new york. the 2016 presidential race hasn't even started yet, but two of the country's top potential candidates are engaged in a political showdown. as jeb bush continues to hit hillary clinton for her use of personal e-mail while secretary of state, he's finding himself at the center of a similar controversy. nbc news white house correspondent kristen welker has the latest. >> reporter: jeb bush making his first 2016 foray to new hampshire. but he found himself quickly on defense. >> we complied with the law. >> reporter: having to explain using a personal e-mail account when he was florida's governor after he criticized hillary clinton for using her personal e-mail when she was secretary of state. >> we've now made all of my e-mails long before mrs. clinton's issues came up, we made them public for you to see. it's totally different. >> reporter: there are new revelations about clinton's e-mails. the state department revealed friday that until recently it had no way of consistently saving senior officials' e-mails, suggesting that some of clinton's e-mails may have been lost. but clinton insist all of her files have been saved. >> those e-mails would be automatically saved in the state department system to meet recordkeeping requirements. that, indeed, is what happened. >> reporter: still, the e-mail flap is a distraction for both potential candidates. >> hillary clinton and jeb bush actually launched their campaign, that would give them both substantive things to talk about. >> reporter: meanwhile, the race inside the gop is heating up, with other potential gop contenders descending on new hampshire this weekend. wisconsin governor scott walker tried to burnish his conservative credentials, suggesting that unlike president obama, he could support sending american troops to fight isis. >> i'm not proposing to engage full-scale boots on the ground, but i'm not taking that off the table. >> reporter: tea party favorite ted cruz and former texas governor rick perry are also paying a visit this weekend. courting the independent voters who make new hampshire the first in the nation's primary so critical. walker also rejected criticism that he's flip-flopped on key issues like abortion. for example, today, walker said he's still pro life. walker also took a swipe at bush saying the party needs a, quote, name from the future to win. a sign that even though the new hampshire primary is about a year away, the race is on. carl. >> kristen welker in washington tonight, thanks. we're learning in the past few minutes a united regional jet had to make an emergency landing this afternoon at chicago's o'hare airport. the plane touched down safely without the nose gear in place for the landing. despite the incident, no injuries were reported. when "nightly news" continues on this saturday, why are so many homes in colorado suddenly exploding? and later, teens taking to the water to learn life's lessons. a different kind of marijuana boom is hitting colorado. home explosions. ever since the sale of recreational pot became legal last year authorities have been dealing with blasts caused by the production of hash oil. a new and dangerous effort to produce a more potent form of pot. our report tonight from nbc's gabe gutierrez. >> fire in the hole! fire in the hole! >> reporter: it's an explosive problem. one that can tear through a home in an instant. captain siegfried cline with the aurora fire department organized this demonstration to show how butane can ignite when amateurs use it to extract hash oil from marijuana plants. a new and dangerous effort to produce a more concentrated form of pot at home. >> and that's the attraction. the purity. it's got a more potent high from it. >> very potent high. >> reporter: windows blown out, kitchens ripped apart. in 2013, colorado saw just 12 of these explosions. but last year that number jumped to 32. dozens of people have been hospitalized. amazingly, no one has died. >> that goes up in a split second. >> very fast. very quick. it's not going to allow people to get out of the area in time. >> reporter: here at the state capital no one would argue that the type of hash oil extraction isn't dangerous, but given that colorado voters have legalized marijuana, the question is, is it a crime. >> i think some districts believe we can already prosecute people for trying to create hash oil at home. and there's other districts who don't think so. so i think it's an area for clarification. >> reporter: the governor's so-called marijuana czar supports lawmakers who right now are trying to regulate hash oil processing. but some feel this is a civil issue, not a criminal one. >> we voted on it. it's legal. it shouldn't be in the criminal system. >> reporter: paul manioni is charged with arson and manufacturing marijuana, after one of these explosions in denver. he's pleaded not guilty. >> the people that were doing this were following colorado law and accidents do happen. but in this country, an accident does not mean that a crime has necessarily occurred. >> reporter: either way, police and firefighters here are on alert. is this one of the unintended consequences of marijuana legalization, exploding houses? >> yeah, it is. it's a very dangerous consequence. >> reporter: a consequence no one expected during colorado's marijuana boom. gabe gutierrez, nbc news, denver. when we come back, nerd alert. one more reason to love pie today. how's this for a birthday celebration? great-grandmother georgina harwood turned 100 this week, and rang in the milestone by, what else, jumping out of a perfectly good airplane. this is the third skydive for the south african native. she completed her first tandem jump at the tender age of 92. speaking of soaring, a bird's stunning flight from the world's tallest building was captured on video today, thanks to a small camera placed on the eagle's back. the bird's-eye view recorded the flight as the bird flew from the top of the skyscraper in dubai to his trainer standing on the ground 2,700 feet below. math lovers and foodies alike also have a reason to celebrate today. march 14th, otherwise known as pi day. it has a special significance this year. nbc's kevin tibbles has more on what all the fuss is about. >> reporter: using the theory of smellativity, we've determined who's your mama's pie show in chicago is the perfect way to celebrate. yes, folks. it's pi day. >> lots of offices do big pi day parties. like 15 pies, 17 pie orders. >> reporter: but pi day is not named for the treat's concocted here. it's for the mathematical delight, pi, spelled simply p-i, or this greek letter, and it's kept number crunchers munching for millennia. simply put, you take any circle no matter what size, and divide the length around it by the length across it, and you always end up with the same number. 3.1415, and on and on for infinity. pretty cool, says university of chicago mathematician amy wilkinson. >> what we would call fundamental constant. it comes up in everything you do in mathematics. >> you can't get away from pi. >> you cannot escape pi. pi is always there. >> reporter: the massachusetts institute of technology put out this video, telling applicants they could log in on pi day 3/14/15 at 9:26 to see if they were accepted. kids at new york's museum of mathematics count down to the moment of pi. of course, here in chicago, what would pi day be without deep dish? at my pi pizza, a slice and a drink today will cost you $3.14, of course. and our facebook friends are sending out all kinds of pi filler to show how they're celebrating. >> pi deserves a day. >> especially if it's pumpkin. >> reporter: so do the math, and have a slice. 3/14/15 won't come around again for another 100 years. kevin tibbles, nbc news, chicago. when we come back, a swim team making waves in more ways than one. we end tonight with a story of a swim team. there are a lot of those, but this one isn't made up of elite athletes, and they're accomplishing what many wouldn't even dare to try. they're learning to succeed out of the water, too. here's nbc's miguel almaguer. >> reporter: hours before most kids think of waking up for school san diego's arch academy swim team, the zombie patrol, beat the sunrise, and the sea lions to the ocean. the water here a bone-chilling 60 degrees. they face it head-on three days a week. this, no ordinary swim, and these students will tell you they're no ordinary teens. >> you've got to know mentally that you're going to be able to do this. >> reporter: the 14 students coping with everything from autism to behavioral issues to learning disabilities put all of that behind when they hit the open waters. >> i hadn't been in a bathing suit for the past, like, i don't know, two years or so. >> reporter: betsy lindbergh who battled a severe eating disorder now has the confidence to do what most would never dare. >> really a feeling of empowerment. knowing once i never thought i would do this. >> reporter: coming to this cove for over a year now, their rigorous training is paying off. last june the teens swam the waters off alcatraz, followed by a relay race that lasted 12 hours off catalina island. the team is just getting started. their biggest challenge is still ahead, a 21-mile relay at the english channel. with each stroke and every swim, lives are changing like 16-year-old laura. >> i remember when i first did to alcatraz, i went over to my mom, and i just cried. she was like, what's wrong? i was saying, i'm just so happy. >> words cannot describe how proud i am of her. she's healthy, she's happy. >> reporter: their strict discipline carries over to the classroom where the students at arch academy attend year around have to agree to stay off social media, and where no dating is allowed. its founder, cheryl zack, saya it gives the struggling students the structure they need to thrive. >> it's really about reaching kids who haven't been able to be reached in other places that they've been. >> reporter: back in the open ocean, the students have proven there's no limit to what they can achieve. >> we did it! >> reporter: winners in the water. and now in life. miguel almaguer, nbc news, san diego. that is "nbc nightly news" for this saturday. i'm carl quintanilla reporting from new york. from all of us here at nbc news, good night. going to happen to us. but it did. >> right now at 6:00 the search is over. sierra lamar's mother tearfully thanks volunteer who have spent the last several years looking for her daughter. good evening i'm terry mcsweeney. >> i'm peggy bunker. a very sad milestone in the case of missing morgan hill teenager sierra lamar. three-year anniversary of her disappearance is two days away. still no body has been recovered. as nannette miranda reports her family and dozens of volunteers have decided today would be the last day of formal searches to look for her. >> we're taking the north end of the island. >> reporter: the last formal search for sierra lamar concentrated in the coit creek area of morgan hill. teams of volunteers braved rugged terrain. looking for clues, any sign of the missing 15-year-old who disappeared nearly three years ago on her way to school. >> we were specially looking for depressions that could have been an easy place to conceal a body and then covered up. >> more than 1100 search team trips have been conducted. they've put in more than 50,000 hours combined. and still no body. it was time