million. >> so, there's a chance! >> there's a chance. >> we can do it! >> we're going to play. thank you so much for joining us. "nightly news" is next. on the broadcast tonight, tragic confirmation. worst fears realized for the family of the last american held by isis. her powerful final message in a letter smuggled to her family. tonight, the mystery of how and when she died. out of control, tempers flare as over six feet of snow piles up on roads and roofs. there's nowhere to put it and there's more snow on the way. caught on camera, a wild chase through southern california, an armed suspect on the run, crashing, carjacking, and a woman's split-second decision at the point of a gun. and chronic fatigue syndrome. misunderstood and often underdiagnosed especially among women. doctors say it's very real, and they're laying out the symptoms to look for. "nightly news" begins now.

>> announcer: from nbc news world headquarters in new york, this is "nbc nightly news" with brian williams. good evening. i'm lester holt sitting in tonight for brian. anxious months and months of hope and worry has turned to unimaginable grief today for the family and friends of 26-year-old hostage kayla mueller. they received the confirmation they had been dreading that kayla is, in fact, dead. her isis captors first reported her death last week, claiming she died in a jordanian air raid but offered no proof at the time leaving her family back in arizona a glimmer of hope. today president obama said about the young aid worker, how she lived her life, she epitomized all that is good in our world. but it is the written words of kayla herself tonight that tell us who she was and define her remarkable courage. joe fryer reports from her home town, prescott, arizona. >> reporter: emotions are strong tonight in kayla mueller's hometown, a year and a half

after she was taken captive by isis relatives say they received a message from her captors confirming her death. >> kayla has touched the heart of the world. the world grieves with us. the world mourns with us. the world wants to be more like kayla. and if that is her legacy and the footprint she leaves on the world, then that is a wonderful thing. >> reporter: u.s. officials tell nbc news the family received a photograph of mueller that appeared to show her dead with trauma injuries, but it's difficult to determine the cause of death. in a statement mueller's parents say, our hearts are breaking for our only daughter, but we will continue on in peace, dignity and love for her. her family also released a letter handwritten by mueller last spring while she was in captivity. i have a lot of fight left inside of me, she wrote. i'm not breaking down and i will not give in, no matter how long it takes. >> i am in solidarity with the syrian people. >> reporter: 26-year-old mueller was working for aid groups along

the turkish/syrian border when she was captured near aleppo in august 2013. in a statement president obama says, no matter how long it takes the united states will find and bring to justice the terrorists who are responsible for kayla's captivity and death. >> on behalf of the people of arizona and the united states congress i want to express the deepest condolences. >> we pray for kayla today. >> reporter: over the weekend in arizona, they prayed for mueller's return. tonight, they're grieving her loss. >> she was a fine young lady. that's for sure. and she's done prescott well. >> reporter: in mueller's letter which was smuggled out by her cellmate, she said at the time she was in a safe location completely unharmed and healthy and being treated with respect. what's unclear tonight is exactly how she died and when. >> joe fryer, thanks. kayla mueller's death follows

months of shear horror, journalists and aid workers beheaded, a jordanian military pilot burned alive. each atrocity bringing new resolve to the fight. president obama is expected to ask congress this week to formally authorize the use of force against isis, though there's a good deal of force being applied already. our chief foreign correspondent richard engel has more for us. richard, good evening. >> reporter: good evening, lester. in many ways, the international coalition against isis has never been stronger. and critically arab allies are now fighting with a renewed enthusiasm. the air strikes are coming harder and faster now, bombing runs by the u.s. jordan and the united arab emirates flying new missions against isis targets in iraq and flying them from jordan showing solidarity after the brutal killing of a jordanian pilot. but isis said the air strikes are not slowing it down and claims they cost american

hostage kayla mueller her life. isis says mueller was in this building near raqqa targeted by jordan at the direction of the united states a claim dismissed by the commander of jordan's air force in an interview with nbc's keir simmons. >> we were miles away. >> reporter: isis also claims the u.s. is allied with syrian president assad because they're both bombing isis. in a rare interview, assad hinted to the bbc that the two countries are in touch, though not directly. >> there's no dialogue. there's, let's say, information. but not dialogue. >> they tell you things? >> some things. >> do you tell them things? >> no. >> reporter: this war is making strange bedfellows. president obama who in 2011 said assad has to go now faces a far more dangerous foe -- isis. but isis has a problem. it's almost out of western hostages. at least one american is still missing in the middle east,

journalist austin tyke. but isis might not have him. they do have british journalist john cantlie and views him as a mouthpiece. in a video released this week, cantlie calls to a isis supporters in the west to launch attacks. with the dwindling number of hostages left to kill, such attacks may be a way for isis to goad the west deeper into battle. having and killing hostages has been a central way for isis to lash out at nations attacking it. now that it is running out of hostages, the fear is isis could look for other ways to do that, lester. >> richard engel tonight, thank you. tonight u.s. officials are telling nbc news the u.s. will announce shortly that it is temporarily closing the american embassy in yemen because of the government's takeover by hardline shiite rebels linked to iran. as unrest grew there three weeks ago, most personnel were already moved out and all but emergency services were suspended. the rebel group announced a

formal takeover of the capital on friday, but the pentagon insisted today that critical american counterterror operations will continue inside the country. tonight the snow has finally stopped falling in boston, for now. but as much as the city wants to dig out and get moving again, tempers have reached a boiling point as most mass transit has come to a grinding halt and there is more snow on the way. nbc's ron mott remains in snowbound beantown for us tonight. ron, good evening. >> reporter: hey, lester, good evening. this should be the evening rush, this whole plaza should be full of people trying to get underground to get a train home. but today there were no trains. that's got a lot of people pointing fingers at the transit chief, and today she fired back. >> in every nook and cranny snow. so much the governor is calling up 500 members of the national guard and asking neighboring states for help. on snow-packed railways,

snowzillas are roaring, jet-powered blowers trying to clear the tracks for the morning commute. all in an effort to stop a repeat of this. passengers stranded forced to walk, trains crippled. >> i want to move. i just want to get out of here. >> reporter: today a demand for answers. >> everybody is tired as heck. they are frustrated as heck. they are mad as heck. and they want all of this snow to go away. >> reporter: boston's embattled transit chief beverly scott redirected blame to the city's aging rail system. >> for anyone to have any belief that a system that's over a hundred years old to think it's going to have the resilience to wind up rebounding and flying like an eagle, that's absolutely the epitome of -- and i'm not going to say foolish. >> reporter: the governor called the disruptions unacceptable. >> we're dealing with unprecedented circumstances here. everybody's scrambling and working enormously hard to deal with all the issues this creates. >> reporter: the heavy snow piling up for weeks, now triggering building and roof

collapses, an urgent plea for people to clear theirs. and with so many homebound, including school kids -- >> they've been out of school more than they've been in school the last few weeks. >> reporter: parents like this woman says stress is piling up like snow. >> the last two days, folks getting into downtown boston from the suburban communities, it's been incredibly stressful on the city as a whole. >> reporter: and there's no end in sight. one suburban town now dumping its snow in the ocean. >> there are two more quick-moving systems that could drop more accumulating snow thursday night and sunday. and then this weekend across the northeast, the coldest temperatures so far this season. >> reporter: now, government offices and schools are set to reopen tomorrow. the t is even promising limited service. of course, there's all this snow to deal with. the mayor is again asking employers to be flexible and let people work from home. we learned today it's now eight babies who have measles in a day care outside chicago which we first reported on last week. this outbreak has spread to at

least 122 people nationwide triggering another alert today from health officials on capitol hill. they hope parents who have been afraid to vaccinate their children can now be convinced to change their minds. our report tonight from nbc's hallie jackson. >> reporter: the baileys in southern california never planned on giving kingston the measles vaccine until now. what changed your mind? >> we had the measles outbreak happening in our backyard. these diseases that i think our generation is not too familiar with. i have to make sure that he's safe. >> reporter: eileen and her husband examples of a new attitude health officials hope to see more of to stop the spread of measles now reported in 18 states and d.c. this year. on capitol hill today, warnings this may grow because of clusters of people who choose not to immunize. >> some of those unvaccinated microcommunities may be getting larger. >> reporter: changing those minds can be hard. a study in "pediatrics" found

pro-vaccine messages actually backfired with some parents already opposed to immunization make them feel defensive and less likely to vaccinate their kids down the road. doctors say another group of people are at risk, too, parents who think it's safer to delay giving the measles shot, like courtney stewart. >> they were babies and i would go in for the vaccine and i felt really nervous, and it made me feel really uncomfortable. >> reporter: she's one of the estimated 13% of people who do not follow cdc guidelines which recommend the first vaccine by 18 months. levi is 5, and this is his first shot ever. >> doing this today, i didn't hesitate. i didn't feel like there was going to be any problems with it. i don't feel bullied into it. how was it? >> reporter: doctors say parents should stick to the schedule since delaying the vaccine can make it less effective. >> a lot of my decisionmaking was based more on fear not facts. if i could go back in time, i really would have done my research. >> reporter: and public health officials hope that message is what spreads now. hallie jackson, nbc news, irvine, california. some terrifying moments

aboard a u.s. airways plane forced to make an emergency landing in houston. it happened overnight aboard a flight out of philadelphia. when it was time to land, the nose gear would not deploy. it wasn't pretty but the pilot managed to rest the plane down easily on that nose. 56 people were aboard, at least one was taken to the hospital with minor injuries. now to southern california on a wild chase through the streets and freeways of los angeles. an armed suspect on the run, police on his trail. a very dangerous situation playing out last night as he slammed into several drivers along the way and then carjacked a woman at gunpoint. all of it caught on camera. we get our report from nbc's miguel almaguer. >> reporter: rush hour in los angeles. a high-speed pursuit for a suspect in a stolen car weaving across freeways through red lights and often the wrong way. >> it's so dangerous. so, so dangerous. >> reporter: the drama televised live. >> we've got police chasing a suspect down there. >> reporter: the intense chase lasts 45 minutes.

>> hitting vehicles left and right. >> reporter: four vehicles are rammed. ditching his mangled car, now he's on foot. a 22-year-old woman is carjacked. >> i see them running towards me. i just kind of froze. i tried to pull my son. i stopped the car and ran. >> reporter: after attempting a second carjacking, the suspect is shot and wounded. >> the suspect is down. >> reporter: incredibly, no other serious injuries. in a city known for wild pursuits, this is one of the most dramatic. miguel almaguer, nbc news, los angeles. >>. >> big news from the world of business and technology. listen to this. tonight apple has become the first american company to close the day worth more than $700 billion. that's roughly the equivalent of $100 for every man, woman and child on earth. not that they're planning on giving it away. still ahead here tonight,

chronic fatigue. a mysterious and often misunderstood disease. doctors say it's very real, and they're laying out the specific symptoms you should be looking for. also, paying it forward. a slice at a time, something really special happening with pizza.

in this day and age, ask most americans if they're tired, and the answer will probably be a big yes. that's why people who suffer from chronic fatigue syndrome can have a hard time being taken

seriously even by their doctors. but today a prominent medical panel declared that this syndrome is not only real, but the vast majority of people who suffer from it haven't even been diagnosed. our report on that tonight from nbc's anne thompson. >> you ready to get dressed? >> reporter: morning rush at this family's home. robin and warren get themselves and their daughters ready for >> don't forget your penguin. >> reporter: but robin battles more than the clock. she has chronic fatigue syndrome. >> no matter how much i sleep, i'm still tired. >> reporter: it started when robin was just 23. after three years of doctors' appointments and tests, she finally got a diagnosis. how hard was it to convince doctors something was wrong? >> it was very hard. so i remember being told that you just need to relax more. >> reporter: calling it a serious debilitating condition. today the institute of medicine issued a new set of symptoms to help doctors recognize the disease. patients must have a drop-off in normal activity for more than six months with profound

exhaustion. sleep that doesn't refresh. and symptoms that get worse after physical or mental exertion. plus either cognitive impairment, what patients call brain fog, or symptoms that only improve when the patient lies down. it affects up to 2.5 million americans more famously laura hillenbrand, author of "seabiscuit" and "unbroken." >> it clearly defines this illness as a physical disease. and i use the word "disease" not a syndrome. >> reporter: that's reflected in the new name recommended by the institute, systemic exertion intolerance disease, a real disease with real consequences for its sufferers. anne thompson nbc news, white plains, new york. our medical contributor dr. natalie azar joins us now. she's a rheumatologist and treats chronic fatigue disease. natalie, how hard has it been to

diagnose and treat this? >> incredibly hard, lester. it's what we call a clinical diagnosis which means there is no diagnostic test. we base it really on the patient's history, physical exam, and excluding other disorders that can mimic it. treatment varies. some people are candidates for medicine, cognitive behavioral therapy can be very effective. exercise can be very effective. but i think what's highlighted in the segment here is it's really brought this syndrome or disease to light, validation to parents and a very good education for physicians across a whole range of disciplines so they can better diagnosis and refer patients to physicians who can manage them. >> a real problem that people are suffering from. >> exactly. >> dr. azar, thanks very much. >> thank you. we're back in a moment with a big show caught on camera at a vegas casino after dark, where things didn't exactly go quite as planned.

if you've ever had one of those days where it feels like

the cosmos is smiling down upon you maybe you were more right than you know. the hubble telescope caught this image that looks an awful lot like a smiley face in space. in actuality, the two points of light that look like the eyes are separate distant galaxies, and the smile is an effect caused by gravitational warping. the biggest show in vegas last night didn't happen on any stage. rather it was the implosion of 12-story clarion casino hotel near the strip known for years as the debbie reynolds, who used to own it. not everything happened as plan. the elevator core remained standing. leaning to the side. crews are now working to finish the job. late word in a big change in late night tv. after years behind the desk job stewart told his audience tonight he'll step down as host of the "daily show" later this year. they call stewart a comic genius, generous with his time

and talent. no word on what's next for stewart. when we come back it's sort of like a take a penny, leave the penny idea. if the pennies, that, added up to pizza. "nbc nightly news" is brought to you by pacific life. for insurance, annuities and mutual funds, choose pacific life. the power to help you succeed.

any office manager looking to boost morale will tell you, so will any parent hosting a sleepover party, few things in this world enjenger as much goodwill as springing for pizza. at one pizza shop in philadelphia, customers can spread that goodwill every time they order a slice. nbc's chanel jones has tonight's "making a difference" report. >> reporter: walk into rosa's fresh pizza, and you'll see, it's not your ordinary pizza shop. lining these walls, thousands of post-it notes, each worth one free slice, put there by a customer who wanted to help feed someone in need by donating a dollar slice. >> thank you. >> we've given away 9,000 slices so far. >> reporter: mason wartman left a career on wall street to run his own business. its own pressure cooker.

>> on bad days i wish i wouldn't do this, and on good days i'm like, i'm really glad i did this. at the end of the day, we help so many people that i can't go back. >> reporter: mason admits he didn't start out intending to feed the needy. it was his customers who cooked up the idea and now keep it going, feeding about 40 people every day. >> i've been doing this. it feels great to be able to help somebody else. >> reporter: they leave a post-it note with a message. do you have a favorite? >> yeah. i like this one right here. it's an angel holding a hot slice of pizza with a little heart inside. >> reporter: it doesn't feel so much like a handout to casey, homeless for six months. >> it's not something you're begging from someone else. the fact that it was a gift makes it taste just that much better. >> we recognize them just like paying customers. just like any other restaurant recognizes their customers. >> reporter: for those in need, it's food for the soul. chanel jones, nbc news, philadelphia. that's our broadcast for this tuesday night. thank you for being with us. i'm lester holt in for brian. we hope you to see you right back here tomorrow evening. good night.

>> it's not just in the schools. it's everywhere. it's in the libraries. it's in the airplanes. it's in the grocery stores. >> right now at 6:00 a father's push to fight potentially dangerous viruses in schools is being heard tonight. good evening, everybody. >> the measles debate is getting heated at a school board meeting tonight drawing national attention. the father of a first grader wants to ban students who have not been vaccinated. nbc bay area's mark matthews is

in tiburon this evening. political power players are also there tonight. >> reporter: we have a couple state senators one state senator and a representative from another and a state assemblyman here. the meeting just getting under way. we first told you about the parents pressing a case with the school here in tiburon. tonight they are asking these state lawmakers to repeal the exemption that allows parents to opt out of vaccinations. this 6-year-old boy cannot be vaccinated because his system is not strong enough. he's been battling leukemia. >> not only would they be at higher risk for more severe forms of illness from measles for example, but likely it would delay their therapy. >> we're hoping there's some person or