end game in libya. thousands of rebels fight their way into the heart of tripoli as moammar gadhafi desperately clings to power. gathering storm. hurricane warnings in the caribbean as a powerful system moves closer to our shores. gold rush. investors are cashing in, and so are thieves. tonight, the new dangers of wearing gold. football scandal. shocking allegations threaten to bring down a college powerhouse. and, swimming with sharks. taking a dip with some of the most dangerous creatures on earth. captions paid for by nbc-universal television

from nbc news world headquarters in new york, this is "nbc nightly news" with lester holt. good evening. after months of bloody stalemates and setbacks in the fight to reclaim their country, libyan rebels tonight have fought their way into tripoli and are waging an all-out assault on the quickly disintegrating regime of moammar gadhafi. as we first reported here last night, the battle for typically had begun. rebel fighters have made steady progress in their offensive on the capital. there are reports they have captured a son of gadhafi. tonight spontaneous celebrations are under way in typically in anticipation that the end is near. u.s. officials tonight have told opposition leaders quite plainly, start planning for the post-gadhafi era. there is late word gadhafi himself is now urgently seeking to negotiate with the opposition. nbc's ief foreign correspondent richard engel has made his way into tripoli and joins us tonight from around a very jubilant crowd. richard? >> reporter: good evening, lester. that post-gadhafi era seems to be beginning right now.

tripoli is falling. we are now in the center of tripoli. people have come out of their homes to celebrate. we've seen fireworks in the sky after a battle today unlike any other in this conflict. it is a march on tripoli. rebels hope it is a walk to freedom. from 42 years of moammar gadhafi's dictatorship. on the highway to tripoli from the west, some rebels carry flags. others drive in cars and trucks. all armed. all excited. with shouts of "god is greatest." they firmly believe after six months of war, victory is close. thousands of rebels who used to fight in small, disconnected groups are now united. some are driving. but most are just walking to tripoli. on this front line in motion, we find a 29-year-old lab technician. he's already walked 15 miles today and won't stop, he says, until he reaches gadhafi's

compound in tripoli. >> i'm one of the people that's going to -- to keep our country free. >> reporter: but there are dangers fighting along an exposed highway. there's little cover. as we film, shots ring out. close. right now we've stopped here because it seems we're caught in the cross-fire of at least two snipers. the rebels fan out, looking for the snipers in a nearby orchard and buildings. they don't find them. with a frontline this fluid, this uncertain, the wounded are just patched up by the roadside. or rushed back to hospitals miles away. but today we also saw victory. as the rebels capture new territory, they rescue some of their own. these men were prisoners taken by gadhafi's troops. disoriented and bedraggled, freed moments ago, after days in dark cells. >> the gadhafi army take me out of my house and they take me to prison! >> reporter: but conquering

tripoli will take more than just will and bravery, both in ample supply here. in a new audio statement broadcast today, gadhafi says he's still in tripoli and urgently calls on his supporters to defend him. and a libyan state tv anchor pulls a gun as she vows never to give up her station to the rebels. but rebels have already taken a military base on the edge of tripoli. it's a different fight now as gadhafi faces a wave of revolution. what we are hearing from people here over and over is that this is a historic day. he said today we live in freedom. that is something we are hearing over and over again. people are saying god is great. they are just thankful. they are thankful that this day has come and now a new future may be beginning for libya. lester? >> richard engel, a scene there that we've seen playing out the

last few months across the middle east. nbc's chief foreign affairs correspondent, andrea mitchell, they're saying to get ready for the post-gadhafi era. how involved will the u.s. be in any transition of power? >> they hope they're very involved. state department officials have been on the ground for several days in benghazi working very closely with the transitional national council. they're appealing to them to not retaliate against gadhafi loyalists and to reach out broadly across all segments of libyan society as they plan for this post-gadhafi libya. of course, there is real concern about the rebel groups' ability to reconcile differences, create a broad-based government. the main concern is to try to avoid civil war as the rebel groups are clearly positioned for victory now as richard engel has shown so dramatically. intelligence experts have been analyzing all of gadhafi's recent statements on the radio and government radio and tv. they do believe he is in tripoli. that he clearly is still defiant. they don't rule out that at some point, especially now that his sons may be in rebel hands, that he could try to cut a deal and leave.

but as always, there is no reliable way to predict moammar gadha gadhafi's next move. >> we're also watching syria, president assad has led a brutal crackdown on the opposition there. he's now come out to say his government is holding firm. he's promising partmentry elections perhaps in february. some political reforms. does he have a chance to defuse things given the climate now of what we're watching in libya? >> one official said that this is sort of delusional dictators day. for assad to go on television and say that he is now willing to promise reform and promise elections just has no credibility with anyone at the white house or the state department. they do not trust his promises. getting him to give up, though, would be a very long process, they believe. despite some signs recently that there are some cracks in the military. so far he's got the money. he's got overwhelming military power. >> andrea mitchell in our washington bureau tonight, thank you. in iran, lawyers for two american men sentenced to eight years in jail on spying charges say they will appeal that sentence.

meantime, the families of shane bauer and josh fattal are pleading with iranian authorities to show compassion and allow them to return home. the u.s. state department says it will continue its call for their immediate release. closer to home, there are hurricane warnings tonight in the caribbean and a major storm irene could be on its way to our shores. for the latest tracking, let's turn to weather channel hurricane expert brian norcross. brian, break it down for us. where is this thing going? >> lester, it is over the virgin islands right now. it is intensifying. and it's heading to puerto rico tonight. take a look at the track and you'll see the cone here aims right at puerto rico and possibility of hurricane force gusts as the storm goes by, as it gets stronger. now, on puerto rico and then downstream, dominican republic and haiti, there are big mountains in there. as we start thinking about the u.s., the question is does it go over those mountains and get disrupted or does it miss to the north? if it misses to the north, we'll be talking about a much stronger storm downstream and we're just

not sure. so the question is when it gets up on thursday evening, do we have as the national hurricane center is forecasting a category 1 hurricane or if it misses those mountains might it be, especially if it's in the northern bahamas or right along the east coast of florida, significantly stronger than that? we cannot rule that out. looking farther downstream, the carolinas are definitely under a threat here as we look toward the end of the week. so this is going to be a very busy week as we head on and look at the east coast there. and we have the dip in the jet stream. that's what's driving it. we'll watch and see exactly how this develops. all right. we'll be with you this week. lester? >> brian norcross. thank you for the update there. the weather was just fine on martha's vineyard today where president obama enjoyed a round of golf. meantime, his supporters and rivals battled it out on the sunday talk show circuit. it all comes amid new concerns tonight about the future of social security. we get our report from nbc's mike viqueira. >> reporter: president obama on

the golf course today in martha's vineyard enjoying his fourth day of a family vacation. while back in washington, a top political adviser insists the coming campaign is not a concern. >> the president's not worried about his job. he's worried about creating jobs for millions of americans who've been out of work for six months or two years or longer. >> reporter: but heading into the 2012 election, neither the economy nor the politics look good for the president. many of his strongest backers including african-americans are openly frustrated. today a leader of the congressional black caucus called for the president to fight harder. >> when he came in, he talked about hope. he talked about jobs. he talked about fairness. he talked about addressing wall street effectively and efficiently. and trying to make a difference. he's got to go back to those basic points. >> reporter: this month more fallout from a weak economy. a new report says funding for federal disability insurance administered through social

security and now paying benefits to 13.5 million americans will run out of money in 2017. due in part to a flood of newly unemployed applicants seeking to replace lost income. one official at the program saying it's primarily economic desperation. meanwhile, former bush and obama aides traded barbs today over the darkening economic picture. >> his policies have utterly failed. this is the seventh or eighth or ninth time we've heard the president talk about producing a plan. >> as someone who's a leader in the white house that turned a record surplus into a deficit, that got us involved in a war that we never should have been in and turned the floor of the new york stock exchange into a casino, i don't think the american people are quite ready to hear a lecture from you on good government. >> reporter: the president is preparing for a major economic address next month. mike viqueira, nbc news, washington. tonight, jittery investors are awaiting tomorrow morning's opening bell after another dismal week on wall street. for a look on what we might expect, cnbc's maria bartiromo. busy week ahead, right, maria?

>> it sure is, lester. new information tonight. we just got word the head of germany, angela merkel, is stepping up her opposition to euro bonds as a way to end the debt crisis in the euro zone. that so far is being reacted to negatively. the big focus, though, next week here at home will be a new focus on the economy. we get the gdp report out. as you know, many economists have been lowering their expectations for economic growth in the u.s. that report will be watched very closely. people expecting growth of about 1%. and then, of course, ben bernanke, chairman of the fed speaking at the annual federal reserve meeting in jackson hole, wyoming. all eyes on that speech. because people want to know if he is going to suggest that the economy needs further stimulus and perhaps we could hear more about qe 3, quantitative easing for a third time. most economists are not expecting new stimulus from the federal reserve. but everything he says in that speech, of course, will be looked at very closely as any hint of whether or not the fed will be here to create some boost to an economy that remains fragile, lester. >> maria bartiromo here in new york with us tonight, thanks.

it was a day of mourning in norway with services across the country to remember the 77 people killed in last month's massacre. at a candlelight memorial in oslo, mourners read the names of each of the victims aloud. the prime minister urged norwegians to look after each other and to watch out for intolerance. in madrid today, pope benedict called on more than a billion young catholics to spread their message. the outdoor mass concluded the church's world youth celebration. there was some controversy over the six-day event's $72 million price tag at a partial cost to spanish taxpayers. organizers say most of it will be covered by registration fees and sponsorships. when "nbc nightly news" continues on this sunday, brazen thieves going for gold. a new warning tonight about your jewelry. later, up close and personal with jaws. and a few of his friends. [ female announcer ] this is not a prescription. this is kate.

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called atrial fibrillation, or afib, that's not caused by a heart valve problem. today we have pradaxa to reduce the risk of a stroke caused by a clot. in a clinical trial, pradaxa 150 mg reduced stroke risk 35% more than warfarin. and with pradaxa, there's no need for those regular blood tests. pradaxa is progress. pradaxa can cause serious, sometimes fatal, bleeding. don't take pradaxa if you have abnormal bleeding, and seek immediate medical care for unexpected signs of bleeding, like unusual bruising. pradaxa may increase your bleeding risk if you're 75 or older, have kidney problems or a bleeding condition, like stomach ulcers. or if you take aspirin products, nsaids, or blood thinners. tell your doctor about all medicines you take, any planned medical or dental procedures, and don't stop taking pradaxa without your doctor's approval, as stopping may increase your stroke risk. other side effects include indigestion, stomach pain, upset, or burning.

if you have afib not caused by a heart valve problem, ask your doctor if pradaxa can reduce your risk of a stroke. we're back now with a look at a gold rush of sorts as the stock market takes investors for a bumpy ride. a lot of people are looking for a safer place to invest. they are increasingly turning to gold. that's causing the price of gold to soar and leading some crooks on a gold rush of their own. we get the story tonight from nbc's aditi roy. >> reporter: they smash.

they grab. and they go. brazen jewelry store break-ins in los angeles and new york. >> there's a lot of jewelry being exchanged for cash, and we don't know who's watching. we don't know who's looking. so we're very, very careful. >> reporter: at a time when gold is more valuable than ever. in the last year, the price has gone up 49%. reaching a high of more than $1,881 an ounce on friday. this has prompted thieves to go for gold in bold ways. even snatching necklaces right off people. in one case, surveillance video shows a robber walking up to a 68-year-old blind woman and pulling a chain off her neck. according to one report, there have been 110 similar cases this year in just one area of downtown los angeles. >> i'm a housekeeper. i wouldn't want to wear anything that would put me in the center

of attraction or center of attention by people who steal. >> reporter: last week police in oakland, california, issued a warning to women. >> if you choose to wear gold, you know, you should at least conceal it under your clothing. >> reporter: thieves often sell their gold to unlicensed gold dealers. one northern california pawnbroker who didn't want his face on camera is worried about the impact on his business. so we hired a private investigator to document how easy it is to sell gold on the street. >> the video showed that the private investigator walks into the shop, sells the jewelry. nobody requires any ids. no signatures required. no fingerprints required. they just walk out with cash. >> reporter: jewelry store owners are trying to fight back. one way is by hiring extra security guards and posting them outside their stores. >> there is definitely a fear out there, you know. we have to take better precautions. >> reporter: as skyrocketing prices drive more and more people to go for the gold. aditi roy, nbc news, los angeles. when we come back here

tonight, they faced the biggest powerhouses in the game and won. but can a storied team survive a massive scandal off the field? it's simple physics... [] a body at rest tends to stay at rest... while a body in motion tends to stay in motion. staying active can actually ease arthritis symptoms. but if you have arthritis, staying active can be difficult. prescription celebrex can help relieve arthritis pain so your body can stay in motion. because just one 200mg celebrex a day can provide 24 hour relief for many with arthritis pain and inflammation. plus, in clinical studies, celebrex is proven to improve daily physical function so moving is easier. and celebrex is not a narcotic. when it comes to relieving your arthritis pain, you and your doctor need to balance the benefits with the risks. all prescription nsaids, like celebrex, ibuprofen, naproxen, and meloxicam have the same cardiovascular warning. they all may increase the chance of heart attack or stroke, which can lead to death. this chance increases if you have heart disease

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we are happy to report it was a much friendlier affair today in shanghai where the georgetown hoyas basketball team exchanged gifts with the chinese team before a game of hoops. quite a different scene from thursday when a game between the hoyas and another chinese team in beijing ended in a hard foul, flying fists and chairs. it has been an offseason of high profile scandals for the ncaa with several major college football programs under investigation. but the latest scandal is proving to be the highest profile of all. the mighty miami hurricanes dealing with a category five controversy involving cash, payments and prostitutes that threatens to bring down the team. our own mark potter has the latest on the storm rocking the "u."

>> reporter: preseason football practice at the university of miami. now clouded by allegations that scores of players received millions of dollars worth of illicit gifts and favors from a school supporter. yahoo! sports reports that nevin shapiro, now serving a 20-year federal prison term for a nearly billion dollar ponzi scheme, claims he lavished u of m players with cash, prostitutes, entertainment in his multimillion dollar homes and yacht, paid trips to high-end restaurants and nightclubs, jewelry and other items from 2002 to 2010. >> it's a huge deal. it's something that's damaging to the university's image nationally. it's something that puts in peril the immediate and even long-term future of the football program. >> reporter: university officials including president donna shalala and new head coach al golden say they are taking the claims seriously.

>> nobody wants to get to the truth quicker than i do. the way you do that is you cooperate. >> reporter: the university of miami which has won five national football championships now joins eight other u.s. schools recently investigated or sanctioned by the ncaa. the national collegiate athletics association has been investigating miami's team for the last five months. its president says if the assertions are true, the alleged conduct at the university of miami is an illustration of the need for serious and fundamental changes in many critical aspects of college sports. but miami fieaker billy corbin who's movie "the u" features the um football team blames school officials who took donations from shapiro. >> one of the university's primary responsibilities is to protect its students. particularly to protect its students from the likes of a nevin shapiro. and the university failed to protect its students. >> reporter: the ncaa says its decision on whether or how severely to punish the school will likely come early next year. mark potter, nbc news, miami.

in what would complete a dramatic reversal of fortune, the sex assault case against former imf chief dominique strauss-kahn could be dropped this week. our nbc station here in new york, wnbc, has learned prosecutors will meet with the accuser tomorrow. her lawyer tells wnbc he thinks it's a clear indication they will ask a judge to dismiss the charges on tuesday. up next here tonight, swimming with great white sharks. on purpose. impressive resume.

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finally tonight, a prospect that might cause more than a few correspondents to head for the hills. a face-to-face encounter in the water with a great white shark. fortunately, our intrepid peter stander bravely took on this assignment. take a look. >> reporter: it is the ocean's most feared predator. the great white shark. under water, they're agile. and above the surface -- unbelievably athletic. displaying rarely seen aerial acrobatics that are, for lack of a better word, jaw dropping. we joined this veteran team of marine experts off the coast of

south africa in what's called shark alley. one of the most notorious great white hunting grounds on earth. that's recently become one of the world's hottest destinations for shark gazing tourists. >> one of the coolest things i've ever done. >> reporter: after less than ten minutes onboard, four great whites attacked the bait around our boat. oh, my goodness. of course, now it's my turn to go face to face with the great white. so it's me, a little bit of metal, and the greatest predator of the open ocean, huh? beneath the surface, it's eerily silent. the murky waters only add to your adrenaline. moments later a 14-foot great white slides into view. then another. and they keep coming. it just shows up right in front of you. literally like three feet ahead of you. when they pass, they make eye contact. you stare into their eyes for a moment. >> i think there's a primal fascination with sharks because

still people believe here's a creature that could be right off my local beach that could eat me. >> reporter: in realtime, their attacks last just a second. blink and you'll miss it. but in super slow motion, they reveal the fluidity and awesome power of these magnificent predators. >> i mean, it was turning in the air and twisting. and its tail was like its rudder. they remind me of really jets or rockets when they blast out of the water. >> reporter: they're intelligent and complex creatures with distinct personalities. a predator unlike any other in the ocean. peter alexander, nbc news, south africa. that's "nbc nightly news" for this sunday. the latest on the situation in libya tonight on your late local news and, of course, tomorrow morning on "today." i'm lester holt reporting from new york. for all of us here at nbc news, goodnight.