slow in the next 30 to 45 >> thanks for joining us. >> good night folks. on our broadcast tonight, school massacre. a terrible tragedy. more than 140 dead, almost all of them children, as armed gunmen storm the campus and open a ferocious attack. threatening violence at movie theaters. the electronic hackers that have taken down sony pictures have gone a step further now, threatening violence, invoking 9/11. nbc news has learned tonight the fbi is closing in. early warning. what are 30-year-olds doing in an alzheimer's clinic? tonight a new approach to battling the awful disease years before the signs start to appear. and over a barrel. as americans enjoy a big break on gas prices, look who's paying the price. "nightly news" begins now. >> announcer: from nbc news

world headquarters in new york, this is "nbc nightly news" with brian williams. good evening. it was two years and one day ago we were trying to process, along with everyone else, the horror we had just witnessed at a school in newtown, connecticut. the world was watching back then as they are again tonight. a school in pakistan was attacked today by the taliban. a suicide squad. and when it was over upwards of 145 people were dead, virtually all of them children. and so today, halfway around the world, parents were yet again looking for children's names on a list. we get our report tonight from our chief foreign correspondent, richard engel. [ sirens ] >> reporter: this was a well-planned massacre, a bloody eight-hour rampage executed without mercy. as the wounded arrived at a nearby hospital, they describe the horror. >> translator: we locked our

classroom door from the inside but three attackers shot their way in and then shot at us. >> reporter: the shah was hiding under a desk and watched in horror as his teacher was killed. she tried to stand up to the gunmen. they shot our teacher, he says, and then burned her body. this reporter was at the scene of today's massacre. >> the assailants took advantage of the broken barbed wire, infiltrated the school, then engaged the guards, killed them, and then went on to till over 130 students. >> reporter: survivors say there were at least seven militants. once inside, they entered an auditorium packed with high school-aged students. one detonated a suicide belt. the others opened fire indiscriminately, then fanned out through the classrooms, firing as they went. pakistani commandos arrived within an hour, but the militants had booby-trapped the school compound. parents, some army officers,

some civilians, gathered outside the hospital desperate for news. >> many of the kids in this school are the children of the soldiers who are fighting on the front lines of pakistan's war on terror. >> reporter: this summer the pakistani army launched a major offensive into the taliban's border area stronghold, flattening villages, confiscating weapons. today's attack was the taliban's revenge. it drew condemnation from around the world, including from pakistan's own nobel laureate malala yousafzai, shot by the taliban for daring to go to school. >> i call upon the international community, leaders in pakistan, all political parties and everyone, that we should stand up together and fight against terrorism. >> reporter: tonight it seems pakistanis may be ready to come together and demand that their government take on those who dare to massacre so many innocent children. this was an absolute atrocity. more than 130 dead children. but brian, it could have been even worse.

the attackers brought with them lots of ammunition, gasoline, food. they planned to stay inside this compound for as long as they could and keep on killing. >> just such a tragedy from overseas. richard engel starting us off here in new york tonight. richard, thanks. the electronic attack on sony pictures took a potentially violent turn late today that's being described in terms of terrorism. the group that has infiltrated the company's computers today made a threat of a 9/11 type attack on movie theaters that choose to show the new movie from sony, a comedy that depicts the assassination of north korean leader kim jong-un. no one is laughing at this. and tonight the u.s. department of homeland security was compelled to say they're aware of the threat but unaware of any credible intelligence to indicate an active plot against movie theaters. nbc's joe fryer has the latest from los angeles. >> reporter: the hackers started releasing their so-called christmas gift today, another huge batch of data stolen from sony pictures.

but with this delivery, the hackers sent an ominous message that goes beyond hollywood. a threat to movie theaters that show the upcoming sony film "the interview." the message says, the world will be full of fear. remember the 11th of september 2001. >> the goal is very clear. they want this movie pulled and not released. >> reporter: "the interview" is a comedy about a plot to assassinate north korean leader kim jong-un. it's due out on christmas. department of homeland security official says they're aware of the threat, but at this time there is no credible intelligence to indicate an active plot against movie theaters within the united states. >> we take those threats very seriously, and we will take extra precautions during the holidays at theaters. >> reporter: still, the movie stars, seth rogen and james franco, have canceled all media appearances including one tomorrow night on "the tonight show with jimmy fallon." federal investigators say they're closing in on the source

of the attack, including the part of the world where it came from. the north korean government has denied any role in the hack. also today the first hack-related lawsuit was filed against sony. a class action suit by former employees. the hackers stole thousands of social security numbers, data about salaries, medical information and more from former and current employees. >> it's almost like sony had a safe deposit box with all its employees' information and left it open for anyone to access. >> reporter: sony declined to comment today on the lawsuit and the hackers' latest threat. joe fryer, nbc news, los angeles. the manhunt that had suburban philadelphia on edge is over tonight. the suspect, bradley stone, former marine suspected of killing his ex-wife and five members of her family. he was found dead in the woods near his home. it's believed he took his own life. according to investigators, he was locked in an ugly custody battle with his ex-wife. the people of australia

awoke this morning to a changed nation, the day after two innocents were killed in an agonizingly drawn-out hostage standoff. tonight we're learning more about the victims and getting an incredible vantage point on the crisis as it unfolded. our own hallie jackson is in sydney for us. good evening. >> reporter: brian, martin place is one of sydney's most popular meeting spots. perhaps it's no surprise this is where people have spontaneously gathered over the last 48 hours, filling this plaza with bouquets and cards. australians showed solidarity and support for the hostage victims. the sea of flowers in downtown sydney grows every hour. >> an act of humanity just because of what happened. >> reporter: just a block from the cafe where the 16-hour siege ended early tuesday. many australians watching it live. the lindt cafe is so close to the newsroom of channel 7, one of australia's biggest broadcasters, that the network set up cameras facing the

windows so police could watch and snipers perched in the balcony with this vantage point as the hostage crisis unfolded. one sniper watched and waited for hours along with cameraman greg parker who captured unforgettable images of terrified hostages standing at the window at gunpoint. >> it was genuinely horrible. in 20 years, you know, it's very rare to come across such upsetting footage. >> reporter: his camera even picked up the police sniper's words when they both heard a single shot. the hostage down was tori johnson, the cafe manager, killed as he reportedly tried to wrestle the weapon from the gunman. >> it doesn't surprise me. he was never going to leave. he never would have left his staff there. >> reporter: katrina dawson also died, a lawyer said to have shielded her pregnant friend from the gunfire. reporter natalie barr knew dawson and learned of her death on the air. >> katrina dawson who i know and

have friends who know. she's the mother of three children. i'm just finding that out. >> reporter: the gunman, man haron monis, was killed as police stormed the cafe. the self-described cleric with a criminal history was not on a terror watch list. >> the individual concerned is obviously -- was obviously a deeply disturbed person. >> reporter: but many here are choosing instead to focus on the victims. >> these heroes were willing to lay down their lives so others might live. >> reporter: remembering their strength and sacrifice. people downtown here have noticed much more of a visible police presence. that will continue through at least the end of the year, not necessarily because of any specific threat, but to give people a sense of safety after the siege. brian? >> hallie jackson in front of that incredibly sad scene in sydney, australia, tonight. as we turn to politics in this country, remember this, americans aged 26 or younger

have only known a republican president named bush in their lifetime. this was in the news today because jeb bush, son of 41, brother of 43, said today he is exploring the possibility of becoming 45. running for president in keeping with what's become the family business. our political director moderator of "meet the press" chuck todd is with us from the white house tonight. how does it help jeb bush by getting on the board early and does it scare anyone off? >> he has to get out early because many people, like myself and others, never believed he was serious about running. now everybody believes he's serious about running, number one. number two, there are a lot of skeptical conservatives, the activist base of the republican party is more conservative than jeb bush is or his brother or his father. and he's got to work hard to win over those conservatives. that's another reason to start early. finally, it puts pressure on the other so-called establishment front-runners, a chris christie in new jersey, a mitt romney was thinking about a third run, jeb bush getting in now makes their

candidacies longer shots today. >> chuck todd on the north lawn of the white house tonight. chuck, thanks. now to geopolitics. as we've been reporting the price of gas continues to get dramatically cheaper across this country. in some places now below $2 a gallon. it's great for those of us who drive. it also happens to be very bad news for vladimir putin. as the falling price of oil sends russia spiraling into an economic crisis possibly, that could have a ripple effect around the world. we get our report tonight from nbc's tom costello. >> reporter: on the streets of moscow, the economic crisis is worsening by the hour with the russian currency in free fall. the ruble has now lost 50% of its value so far this year with the price of oil also in free fall, going from $115 a barrel to $60 just since june. the problem for russia nearly half its revenues come from oil and gas. and moscow is still facing crippling sanctions over its actions in crimea and ukraine.

>> it will be up to president putin to decide whether or not these economic costs are worth it to him and are worth it to the russian people. >> reporter: today the russian foreign minister was defiant. >> i can assure you that russia will not only survive but will come out stronger out of this. >> reporter: but the international banking community is losing confidence in russia. >> this crisis is really hurting the average russian. when they go to the store and all the food that they buy that is imported, it's going to be a lot more expensive. >> reporter: while the drop in oil prices may mean sky high inflation in russia, it's been a boon for americans. more than half the country is now paying less than $2.50 a gallon. gasbuddy.com national map shows who is paying the most, in red, and who is paying the least, in green. in some cities now under $2.00 a gallon. $1.98 in st. louis, $1.88 in oklahoma city and $1.86 in baton rouge. why are oil prices dropping?

analysts say saudi arabia is flooding the market with oil to drive competitors like the u.s. out. tom costello, nbc news, washington. still ahead for us on a tuesday evening, a new approach to preventing alzheimer's. how doctors are training 30 and 40-year-olds to fight back against this awful disease decades before the symptoms begin to appear. also tonight, the heartwarming and hilarious moments that millions of americans are sharing that have been judged the year's best.

cases of alzheimer's

continue to grow in this country. more than 5 million americans are living with it, and we're told that number's expected to triple by 2050. with no effective treatment yet, prevention is the new frontier. and the key to it may come much earlier in life than previously thought. our report tonight from our chief medical editor, dr. nancy snyderman. >> reporter: 32-year-old musician and filmmaker max lugavere does not look like someone worried about alzheimer's, but he is. what did you see in your mom that concerned you? >> my mother who is 62, three years ago started having symptoms of memory loss and cognitive difficulty. so i became obsessed with this idea of taking steps in my own life that could potentially ensure that i'll never have anything like dementia. >> the results are fascinating. >> reporter: in hopes of warding off the disease by intervening at a young age -- >> what kind of memories is this testing for? >> reporter: -- he's participating in a unique alzheimer's prevention clinic at presbyterian weill cornell medical center.

>> what brings this home for me is my uncle bob. >> reporter: clinic director dr. richard isaacson, who has alzheimer's in his own family -- >> that's my uncle bob. >> reporter: -- designs personalized programs for younger people like max who may be at risk. >> your brain is processing really well. >> i try to use a person's genetic background to help me refine or fine tune the suggestions i make to patients. >> reporter: while young and seemingly healthy, max's blood tells another story. he has a genetic variation and high levels of an amino acid associated with an increased risk for dementia. >> blueberries. >> reporter: to reduce those levels, he's changing his diet and lifestyle. playing music may also reduce the risk of dementia. >> lifetime musical experience as well as midlife onward musical experience can absolutely -- it's been proven to delay cognitive decline. >> reporter: dr. isaacson believes delaying cognitive decline could be the first step in warding off alzheimer's

disease. >> we have to empower young people and people of all ages to make brain-healthier choices. >> reporter: this is so important because the brain changes leading to alzheimer's can start as early as 20 years before symptoms show up. this is the new frontier, brian. >> thinking about that guitar i have in the corner. nancy snyderman, we'll take the good news. thank you very much. >> it is good news, you bet. we're back in a moment with the newest additions to the list of the greatest of all time. big changes coming soon at the drive-through perhaps.

a lot of numbers making news tonight, starting with our new nbc news/"wall street journal" poll. it shows 51% of americans believe the interrogation practices detailed in that so-called torture report were acceptable. 28% say they went too far. and further, 45% say they should be used in the future. here's another number. 98.6. we equate that with normal, but in this context it's high.

aaa expecting 98.6 million of us to be on the road over christmas traveling 50 miles or more. that would be a record. and the top google searches of 2014 are out. number one was the late robin williams. followed by world cup, ebola, malaysia airlines and the ice bucket challenge. they're also broken down by nation. in ukraine, for example, the most googled recipe was how to make a molotov cocktail. the complete list on our website. norman bridwell has died. he was the creator of clifford the big red dog. his idea was initially rejected by 15 publishers. now there are 129 million copies of his clifford books in print, say nothing of the tv show, the toys. clifford was based, by the way, of his wife's childhood imaginary friend. norman bridwell was 86 years old. this year's rock and roll hall of fame inductees, green day, joan jett, ringo starr, bill withers, and some who are no longer with us. lou reed and the great stevie ray vaughan.

the entire list on our website tonight. induction set for cleveland in april. you can just hear it from mcdonald's fans. say it ain't so. the chain is experimenting with some menu changes at certain restaurants in six different states. with sales down almost 5%, they're trying to keep up with the times and market tastes. so they're trying out fewer types of chicken sandwiches, fewer wraps and going from four versions of the venerable quarter pounder with cheese to just one. it's one of the truly few burgers ever truly immortalized in a modern classic. >> you know what they call a quarter pounder with cheese in paris? >> they don't call it a quarter pounder with cheese? >> no, they got the metric system. >> what do they call it? >> they call it royale with cheese. >> we had to do that. the chain says a simpler royale with cheese is just a step toward a simpler menu. another break. and when we come back, we could all use this one on a day like today. the downright most inspiring and joyful viral videos of the year

thus far.

it has, admittedly, been a rough news week so far and it's only tuesday. when confronted with the kinds of headlines we've seen in recent days, we do the same

thing a lot of folks do. a friend of ours likes to surf the internet and come up with something positive. so nbc's kevin tibbles gathered the best viral videos of the year thus far and has our report tonight. >> i don't want him to grow up. >> reporter: from a big sister's wish pulling the heartstrings of 30 million online viewers. >> do you want him to stay little forever? >> yeah, he's so cute. >> reporter: it has been a most wonderful year of browsing for inspiration. but news that mom's expecting doesn't inspire this little fella. >> what were you thinking? >> reporter: who throws a prepartum tantrum. >> this is exasperating. >> reporter: 8-year-old liam fitzgerald has down syndrome, has beaten leukemia and is as tough as the boston bruins he loves. >> jp gibson has come into the game. >> reporter: 5 million have seen 5-year-old j.p. gibson, also fighting leukemia, slam dunking with the utah jazz.

>> he rises to the rim and hammers! >> reporter: while 8 million shared kelly gunderson's joy as her mom, suffering with alzheimer's, suddenly recognized her again. >> well, i love you, kelly. >> i love you, mama. >> reporter: casey the schnauzer a woman's best friend fainted with excitement. viewed 38 million times. and tara is no scaredy cat. she came to the rescue of a young boy attacked by a dog. >> those are tickets to trinidad. >> reporter: who says the internet is all frivolity? 18 million shared as a canadian bank machine dispensed airline tickets so a mom could visit her sick daughter. >> thank you for your service. >> reporter: and charity runners paused to honor a 95-year-old veteran. >> you're doing a good job. >> reporter: mining the web for a few hidden gems can sometimes remind us of who we are and the wonderful things we're capable of. >> you can be brave also.

>> reporter: kevin tibbles, nbc news, chicago. that is our broadcast on this tuesday night. thank you for being here with us. i'm brian williams. we hope to see you right back here tomorrow evening. goodnight. i was inside the house and all of a sudden, it starts shaking, like an earthquake. >> right now at 6:00 p.m., the earth is on the move. all this rain uprooting trees and causing hillsides to slide. and it's not over. looking live at live radar, you can see a new round of rain is coming down right now. good evening, and thanks for joining us. >> more problems tonight across the bay area. this is the first of three storms moving through.

we'll start in the north bay, the focus now is the rain triggering mud slides. we have a team of reporters this evening. mark matthews is tracking those mud slides, ninette reports from the south bay. we begin right here in the studio. jeff, where is the bulk of the rain right now. >> right now at the immediate coastline, the peninsula, san francisco getting nailed over the past 30 minutes with some very heavy rain fall, even a few hail reports. rain fall rates approaching one inch per hour and with all of the rain over the past two weeks, flooding concerns will be up there if you don't have to be on the roadways, go ahead and stay inside tonight. you can see with this particular area right across san francisco, three quarters of an inch per hour. that will be good enough in downtown, to send water into the muni stations and bart may have trouble taking on this water. 280, highway 101, this is the number one worst concern right now -- not a good idea to be out here on these roadways with t