it is just not feeling it. >> 83 in oakland. >> "nbc nightly news" is next. thank you for joining us. on this saturday night -- secret mission -- the sudden release of two americans by north korea after a high-ranking u.s. official negotiates their freedom. historic choice -- the woman who's taken down mobsters and terrorists now tapped to be the country's next attorney general. a good night's sleep, and why it's becoming harder to get for more and more kids. the new research that shows what happens as they get older. and -- to the rescue, delivering life-saving equipment fast in medical emergencies. is there a role for these unmanned drones?

good evening. two americans being held in north korea are on their way home to the united states tonight. freed this morning after a secret mission by this country's top intelligence official. kenneth bae in prison for two years and matthew miller held in north korea for seven months are flying back to the united states with u.s. director of national intelligence james clapper, who made the trip to pyongyang earlier this week to secure their release. clapper is the highest ranking american official to travel to the reclusive nation in 14 years. while today's news is cause for celebration for both men's families, the exact nature of the talks that led to their remains cloaked in secrecy. we have two reports beginning with nbc's chris jansing at the white house. chris, good evening. >> reporter: good evening, lester. the official u.s. government statement said simply, they're on their way home. an understated description for the highly secretive,

high-stakes mission. adding to the intrigue the man who helped win bae and miller's release is america's top spy, james clapper. he's on the plane with them right now, on the last leg of their journey to freedom. the long nightmare for kenneth bae and matthew todd miller ended dramatically, like something out of a spy novel, the central character in the top-secret mission to win their release is america's top intelligence official james clapper. after abruptly canceling a speech in new york earlier this week, he flew to pyongyang for the high-stakes negotiation. >> this was the final step in a very well-choreographed ballet. this was something that had been predetermined. so there was no real uncertainty when he arrived in pyongyang as to the fact that he was going to bring these two guys back. >> reporter: bae's family had campaigned tirelessly for his return. and said in a statement, we have been waiting for and praying for this day for two years. our thanksgiving celebration this year will be one we will never forget. >> i think it's a wonderful day for them, their families.

obviously, we're very grateful for their safe return. >> reporter: miller had been arrested this spring after reportedly ripping up his visa at the airport, charged with espionage and sentenced to hard labor. bae, an korean-american missionary, had been held for two years, in a labor camp and then in a hospital in failing health. but he sent a message to his family back in february. >> i have not lost hope or i have not given up anything. >> reporter: the release comes weeks after jeffrey fowle returned to his family after six months in north korea. he spoke to us by phone. >> i'm very happy. all three americans are back home, or on their way back home at least. that's a good thing. >> reporter: their release leaves no known american prisoners in north korea, a communist country cloaked in secrecy with an unpredictable leader. what is still an open question is north korea's motive in all this and does it mark a broader shift in

policy for this country. lester. >> nbc's chris jansing tonight, chris, thanks. our chief foreign affairs correspondent andrea mitchell has more now on today's release and what was behind it. andrea, should we view this release in the context of a bigger picture? >> reporter: lester, good evening. officials say no. the top spy to america's mysterious armed missions the cia has not been able to penetrate does not signal a diplomatic opening. general james clapper, i'm told, did not meet with north korea's mercurial young leader kim jong- jong-un. but they tell me the u.s. spy chief was carrying a brief message from president obama to him. i'm told the message was short and to the point. the general was the president's personal envoy just to bring home the two americans. u.s. officials are saying this does not mean a warming of relations. they say that will not happen until north korea stops violating agreements to get rid of its nuclear weapons program and stops launching missile tests. in another big obstacle, by the way, to normalizing relations north korea has just been found guilty of horrendous human rights abuses at its notorious prison camps by the u.n. and is

facing condemnation by international tribunal, an issue experts say has been worrying the north korean regime. it's significant that general clapper is the first cabinet official to go to pyongyang since then secretary of state madeleine albright in 2000. even though john kerry was nearby at the time in neighboring beijing, it was decided not to send a diplomat to avoid any signal of an opening to the north, lester. >> andrea mitchell, thank you. president obama announced a historic choice to be the country's chief official, he nominated loretta lynch the top federal prosecutor in brooklyn to be the next attorney general, replacing eric holder who is stepping down. we get more tonight from nbc's kristen dahlgren. >> thank you, everyone. >> reporter: flanked by president obama and outgoing attorney general eric holder, loretta lynch accepted the nomination for what the president called the people's lawyer. >> i will work every day to safeguard our citizens, our liberties, our rights and this great nation which has given so

much to me and my family. >> reporter: the 55-year-old is currently the u.s. attorney for eastern new york, known for tough convictions like the new york police officer who assaulted abner louima. >> loretta might be the only lawyer in america who battles monsters and terrorists and still has the reputation for being a charming people person. >> reporter: the daughter of a librarian and minister, lynch is a wife and stepmother, harvard educated. and if confirmed would be the first african-american woman to hold the post. significant to civil rights leaders since the next attorney general will oversee federal investigations, including the one in ferguson, missouri. >> i think loretta lynch certainly satisfies all of us that she will continue in the same vein that eric holder had began. >> reporter: while the president urged a speedy confirmation, republicans may not be as quick to push lynch through a lame duck congress. senator charles grassley saying he ekt ed lynch to get a fair

but thorough vetting. while presumptive senate majority leader mitch mcconnell said her nomination should be considered in the new congress. what could be a high power partisan battle shaping up over a woman the president says has always been more about making a difference than making headlines. kristen dahlgren, nbc news, new york. in iraq today a series of bombings in and around baghdad killed more than 40 people, just the latest attacks in a wave of violence. at least some being tied to isis militants. it comes one day after the united states announced a significant escalation of its role in iraq authorizing an increase in the number of u.s. troops from 1,400 to almost 3,000. for more on the expanding u.s. mission in iraq, we turn to retired four-star general and nbc news military analyst barry mccaffrey. general, thanks for being with us.

these role, they will be training iraqi troops. so my questions to you are, haven't we already done that? and will it make a difference? >> well, it's hard to imagine, you know, one-quarter of the iraqi army took off like wild hares leaving their billions of dollars worth of u.s. tanks and aircraft up in mosul. so training isn't the issue. the problem is political reliability, the quality of their leadership and then finally the big mission to us, lester, is the security of our 5,000-plus people at the u.s. embassy in baghdad. this is a dangerous situation. >> well, what kind of force would be required to turn the tide in this? and of course you can't ask that without talking about the possibility of mission creep on the part of the u.s. >> well, you know, i think the administration very sensitive about the boots on the ground and mission creep criticism, but the bottom line to all this is, you know, thank god for u.s. air and naval power. they are hammering the isis insurgents particularly when

they mass around places like kobani. but at the end of the day it's a ground battle. and the iraqi army is unreliable, they're a shiite repressive force. there are shiite militias that are menacing the sunni civilian population. iraq has come apart. it's hard to imagine that the iraqi army's going to put it back together again. >> a sober assessment. general mccaffrey thanks so much for being with us. >> good to be with you, lester. there's new outrage in mexico tonight after authorities there announced that dozens of college students missing for six weeks are now presumed dead in what appears to be a horrific mass murder. the students were abducted in the southwest city of iguala. we get more from nbc's gabe gutierrez from mexico city. >> reporter: the mass murder of 43 college students was chilling. mexican authorities say drug gang members confessed they packed bodies so tightly into a dump truck that 15 young men suffocated to death. the rest were shot, the bodies

burned for 15 hours, then dumped along the river. >> it was obscene. i mean, it's absolutely barbaric. >> reporter: the students went missing six weeks ago, sparking nationwide protests. even for a country used to drug violence and disappearances, more than 26,000 over a six-year period, these kidnappings have struck a nerve. these were just students. on september 26th a group of first-year students drove to a protest in iguala, a city three hours outside the capital. prosecutors say the mayor and his wife, a couple with ties to organized crime, ordered the local police to stop them. in an ambush police killed three students. and authorities believe the corrupt officers later handed the remaining 43 to a cartel. omed garcia barely escaped the gunfire. "police wanted to kill us," he told me. federal authorities did not launch an investigation until ten days after the students went missing. and riots broke out. this is the inside of iguala

city hall. after the students disappeared, protesters set it on fire. it's become a grim reminder of the violence that has shaken this city. now detained, 74 people including dozens of local police, the mayor and his wife. >> this event that kind of reminds us all that organized crime is very -- continues to have a very strong presence in certain parts of the country. and they're very much linked to politics and politicians. >> reporter: the students, seen in this school video smiling a month before they disappeared. ceasar juan kwz gonzalez is one of the missing. his father, a farmer, says his only son recently enrolled at the college in search of a better life. tonight he is being remembered by a nation outraged by this massacre. gabe gutierrez, nbc news, mexico city. in this country a fourth teenager has died after being shot by a classmate two weeks ago at a high school in washington state. 15-year-old andrew fryberg was among those shot when his

cousin, jaylen fryberg, opened fire at a group of students sitting in the cafeteria. the shooter also died after turning his gun on himself. much of the country's about to see a big change in the weather as a huge wave of cold air starts to descend from canada with high temperatures well below average. weather channel meteorologist mike seidel is in minneapolis watching it all for us. mike, what are we looking at here? >> reporter: hey, lester. just about everyone in the eastern two-thirds of the country is looking at their temperatures taking a nose dive. here in the midwest we're talking about shivering and shoveling. we have winter storm watches and warnings flying from minnesota, across parts of minnesota and wisconsin. a swath of snow spreading east sunday night and monday. could be as much as a foot of snow. for many, the first time you have to shovel. chicago, you get off easy, no snow this time. the biggest impact will be the blast of arctic air. look at these monday highs in the 20s. nearly 25 degrees below average. on tuesday it's a blue norther, a cold wind sweeping into texas with crashing temperatures.

but look at that high temperature in casper, only 12 degrees. the big chill continues to move east wednesday. chicago struggles to freezing. and the first subzero lows are likely in the high plains. back here in minneapolis/st. paul, we're forecasting at least 11 straight days below freezing. that would tie the second longest stretch on record in november. lester. >> mike seidel for us tonight. thank you. when "nbc nightly news" continues on this saturday, the new research on kids and sleep. what we're learning about how they change. later, one of the hottest trends in the food world and how it's giving some a fresh start.

if you have kids at home, then you're probably all too familiar with the challenges they face in getting enough sleep and getting through the school day. new research out this week found that the problem only gets worse as kids get older. we get more on all this tonight from nbc's miguel almaguer. >> reporter: it's the sound so many of us dread every morning. for 9-year-old finli riley, an early start even on this saturday. >> good morning, baby girl. >> reporter: like so many children her age, she's getting less sleep every year. >> how'd you sleep? >> reporter: school days are never easy. >> sometimes i just want to put my head on my desk and just fall asleep at school. >> reporter: experts say finley is part of a growing trend of children going to school fatigued and losing valuable sleep as they age. a new study from brown

university tracked 94 children for two years. researchers found the typical 9-year-old falls asleep at 9:28 p.m. but by age 11 their bedtime naturally shifts to 10:00. 15-year-olds went to bed just after 10:30. two years later they too stayed up an extra 30 minutes. problem is the morning bell time at school stays the same. >> we end up in a position of chronic insufficient sleep. >> reporter: studies show the lost sleep affects academic performance and could contribute to obesity. it's estimated 40% of high schools in the u.s. start school before 8:00 a.m. >> good morning teachers and students. >> reporter: this year more schools like this one in south carolina are following recommendations from the american academy of pediatrics, sliding its start time from 7:45 a.m. to 8:35. >> i definitely think i see

effects of not enough sleep in them. would love to see them have a few extra hours. >> i have the alarm go off, just like, oh, i want to get back in bed. >> reporter: no matter how old you are, getting out of bed may never be easy. miguel almaguer, nbc news, los angeles. up next, getting life saving medical equipment to those in need. soon it could arrive by drone.

ever wonder what it looks like from inside of a water bubble? the astronauts aboard the international space station did. so they stuck a gopro vitd owe camera inside one and got to see for themselves as the bubble and camera floated around in weightlessness. it was actually a serious side to the exercise to better understand how water behaves in space. looks like it was fun though. as we've seen in recent years, the use of unmanned drones is becoming more and more common, especially in the military and increasingly in business. in the netherlands, one man is testing another use that might help save lives in medical emergencies. we get the story tonight from nbc's ayman mohyeldin. >> reporter: it's the difference between life and death. >> i think he had a heart attack. >> reporter: waiting for paramedics to arrive, agonizing minutes. but life saving help may be soon coming from above. >> the ambulance drone is on its

way. >> reporter: this 23-year-old belgian student came up with the idea of a life saving ambulance drone as a graduation project. with its built-in defibrillator, a camera can beam realtime instructions provided by emergency operators. all designed to save time shaving long minutes off the average response time of a street ambulance. he says his research suggests the ambulance drone could dramatically increase chances of surviving a heart attack. most people they hear the word drone and associate it with killings and death. you're trying to change that. >> yes. so i'm trying to change this perception that drones cannot only do those bad things, but can also do very good things for our society. >> reporter: for years, drones have been used by the u.s. military as lethal killing machines, but now more and more companies are trying to expand how they're used. dominos is experimenting with drones to deliver pizza. amazon.com is developing a drone delivery system. and farmers are using drones to help protect their fields, in this case from wasps.

and while the ambulance drone is just a prototype and a few years away from actually saving lives, it has already changed one life. you're a popular guy on campus these days, right? >> at the moment i'm very popular, yeah. but, yeah, that definitely changed my life. and a lot of companies are contacting me. but my first purpose is to see how we can take this to the next step. >> reporter: the next step maybe, but more likely the next flight. ayman mohyeldin, nbc news, the netherlands. we're back in a moment with some food for thought. how to keep young offenders from landing back in jail.

finally tonight, some of the tastiest food around is being served up by an unlikely group of young people finding a road to success right on the road. here's nbc's rehema ellis. >> reporter: the booming food truck business is changing people's eating habits. >> i got the grilled cheese and the brussels sprouts. >> reporter: it just sounds good. >> it's so good. >> reporter: but this truck in new york city is also changing lives. >> this is my first job ever in my life. >> reporter: this is the first honest, legal job you've ever had in your life? >> yes. >> reporter: 24-year-old christopher thomas got into trouble at a very young age. this is terrific. after multiple incarcerations, chris was selected to

participate in a new nonprofit program called drive change, given a second chance to learn gourmet cooking. and now he helps operate snow day, a state-of-the-art food truck. a recipe to help young ex-offenders find jobs, cooked up by jordan lexon while teaching high school at new york's rikers island, a city jail. >> 70% of the young people i worked with, 16, 17 and 18-year-old young men, were recycling back into the system. >> reporter: it's a nationwide problem. two out of every three released prisoners are re-arrested within three years. >> or have a grilled cheese. >> reporter: warrant waterman knows the challenges. >> i know nothing in life is easy. >> reporter: he spent 13 years behind bars. >> i know what it's like to be young and having felony convictions on my record and trying to find a job and having countless doors close. >> reporter: but waterman didn't give up.

in jail and after he took courses and earned a business degree. he owns a catering company and now mentors the team of 12. >> i think i'm contributing to make them look at things from a different perspective. when you put your mind to something, no matter what it is you can push through, you can persevere, you can succeed. >> reporter: the snow day team spends eight months learning the business, marketing, social media and money management, all while earning a livable wage. is the food truck team making a difference in your lives? >> we're making money and that's motivation to not be in the streets and stay out of trouble. >> it's definitely a game-changer to me and everyone. >> i want people to know to never give up. that there's always hope out there. >> reporter: one young team with a truckload of determination to make a fresh start. rehema ellis, nbc news, new york. that's "nbc nightly news" for this saturday. i'm lester holt reporting from new york. i'll see you tomorrow morning on "today" and then right back here tomorrow evening. good night.

two americans on their way back to the u.s. after being freed. more on their mission. and mourning at the san francisco zoo. just a tragic story. the youngest gorilla dies unexpectedly. the accident that has animal lovers wondering exactly what happened. good evening to you. thank you for joining us. i'm peggy bunker. >> and i'm terry mcsweeney. she captured the hearts of animal lovers. kabibi was one of few gorillas born in captivity and now the san francisco zoo is moirning her death. christie smith live at the zoo, and you just talked to some people who were at the zoo. >> reporter: yeah, they were stunned and saddened to get the news. but as you said, the san francisco zoo is in mourning tonight after a tragic accident. they did release a statement saying that zoo staff was carrying out their standard routine. this actually happened on friday night when they move animals into their night quarters. that's when