this is "nbc nightly news." th u.s. economy is once again in the crosshairs. a downgrade of america's debt by a ratings agency. standard and poors could well impact stock markets around the world tonight and our own tomorrow morning. politicians meantime are debating how the downgrade may affect your pocketbook and whether the u.s. truly deserved it. we have complete coverage tonight. cnbc's washington's john harwood starts us out. >> reporter: obama administration's officials remain furious about s&p's decision to downgrade debt. but they also have to worry about minimizing its effects. hoping to calm markets, treasury secretary, timothy geithner ended uncertainty about his future, wi announcing he'll remain on job rather than return to new york. in an exclusive interview, git anywhere said u.s. treasuries remain safe and sought to reassure americans worried about interest rates on mortgages and auto loans, while blasting s&p's decision. >> i think s&p has shown really terrible judgment and they've handled themselves very poorly and showed a stunning lack of knowledge about basic fiscal math. >> reporter: but the president, who returned from camp david this afternoon, face as huge task as a brewing debt crisis in europe compounds economic jitters around the world. stocks in israel, dubai and saudi arabia dropped over the weekend. if the same happens in asia, that could rattle american investors tomorrow morning. >> the initial reaction in my judgment is going to be negative. what i think the s&p thing did was to hit a nerve. that there's something basically bad going on. and it's hit the self-esteem of the united states. the psyche. >> reporter: s&p officials warned of one in three chance of a downgrade next year if america's fiscal situation gets worse. or political gridlock. so far, there's no sign that either republicans or democrats are turning down the heat. >> this is the tea party downgrade because a minority of people in the house of representatives countered even the will of the republicans in the united states senate who were prepared to do a bigger deal. >> well i agree that there's dysfunction in our system and a lot of it has to do with the failure of the government of the united states to lead. >> reporter: the big question is when the economy will start growing faster and adding jobs. secretary geithner expressed confidence that at least the u.s. can avoid a double-dip recession. >> our country is much stronger than washington. we're a very strong country. and i have enormous confidence in the basic regenerative capacity of the american economy and the american people. >> reporter: and carl, even as republicans criticize the white house over the downgrade, secretary geithner turned it right back on congress, saying they own our credit rating, because they have the power of the purse. >> john harwood at the white house tonight. for more on the global impact, we're joined by cnbc's michelle ka russo cabrera in rome and cnbc's chief economics reporter. >> what happens to the markets could set the tone for the dow here tomorrow. >> absolutely, carl. and countries around the world seem rattled by the u.s. downgrade as well. markets in the middle east sunday, today, were open and they tumbled badly. new zealand just opened, it's down as well. as for here in europe, ironically enough, they have even bigger debt problems. there are three countries here, portugal, ireland and greece that cannot pay their bills without the help of a bailout. and the situation was growing so bad, that just an hour ago, the european central bank annoyanced new measures to help this country, italy, stem off any more problems. we'll see if that has an effect on worldwide markets tomorrow, as well. >> problems on both sides of the atlantic. steve, does this downgrade from s&p hit americans' pocketbooks at home or not? >> there's plenty of confusion and concern about that, carl. we've never been in a situation where the world's benchmark debt, the united states, has been downgraded. so anybody who claims to know what they're talking about here, probably is making it up. there is concern, though, about interest rates, mortgage interest rates, credit card interest rates, some concern it may go up. but i will tell you, plenty of speculation on the other side that we've seen the worst of this. the market anticipated this and it's going to digest this latest bad news with pretty good equality the way it has with other things. >> michelle, steve, thanks. a quick program note there will be special coverage tonight on the markets, beginning at 8:00 p.m. eastern on cnbc. tonight we're learning more about the attack on a u.s. helicopter in afghanistan that claimed the lives of 30 americans in the deadliest single incident since the ten-year war began. for that we go to nbc's ati atiya abaoui in london. soip a senior defense official has confirmed that all remains have been recovered from the crash site. but the effort to retrieve the wreckage is still under way. amid the confusion and grief, new details emerged today about the deadly attack. the chinook helicopter carrying 30 americans and eight afghans was engaged in a rescue mission when it was shot down. u.s. officials say it was brought into the village of tangi in wardak southwest of kabul to help a u.s. army ranger unit that came under fire as it was searching for a dal ban leader. the rescue team reportedly completed its mission, somebody duing the attackers and it was leaving in the helicopter when it was hit. >> there were a handful of taliban probably employing an rpg-7, which is 1960s technology, direct-fire anti-tank rocket. they brought down this very sophisticated helicopter. >> reporter: today a villager described what he saw. >> translator: after it crashed, it caught fire. a huge fire. we were not able to come out during the night because americans were around. in the morning, we saw the american bodies. >> reporter: the 38 killed including 22 u.s. navy s.e.a.l.s, five army air crewmen, three air force airmen, as well as seven afghan commandos and an afghan interpreter. a dog, part of a navy s.e.a.l. team was also killed. some of the americans were from s.e.a.l. team 6, the same unit that hunted down and killed osama bin laden. today nato forces were recovering remnants of the helicopter as american and afghan troops continued to battle insurgents in the area. >> translator: the helicopters are still patrolling over the village. and right now the taliban are fighting with them. >> reporter: this remote mountainous region is filled with fighters from the haqqani network. a brutal and deadly group committed to killing foreigners and anyone who gets in their way. the violence continued in afghanistan today, as nato announced the deaths of four more service members in the south and east of the country. carl? >> thanks. tonight we're hearing from the families of some of the americans killed in that attack. nbc's tom traung joins us from nor fauk, virginia, home to s.e.a.l. team six. good evening. >> reporter: good evening to you. here in the greater norfolk area, it's home to the navy. at a church service in virginia beach this morning, the faithful parade for the fallen and sang the navy hymn. navy s.e.a.l.s may be shrouded in secrecy. but in naval communities like this, they're neighbors, friends and family. >> my heart goes out to them. i know the boys were doing what they loved and always would do that and they live for that. but to lose them, is tough. >> navy s.e.a.l. aaron vaughn was based in virginia beach. he was one of 22 s.e.a.l.s killed in the attack. the 30-year-old leaves behind a wife and two young children. his grandmother wishes she could have seen him one last time. >> i would say aaron, you make me proud. and i'd say, you did a good job. and i'd say, i love you and i always will. >> cynthia morrison with the navy s.e.a.l. foundation, a nonprofit supporting s.e.a.l. families, estimates that half of the 2600 elite commandos are based in the greater norfolk area. the other half call coronado, california and san diego home. and in such a small group, the loss of 22 is magnified. >> we pray every day that they do come home. and this weekend, unfortunately, there are going to be a lot of guys not coming home. >> reporter: eight other u.s. service members died in the crash, among them air force tech sergeant john brown, a native of northwest arkansas. his mother called the special forces medic a humble healer. >> if there is a comfort in the situation, i'm so proud of my son. so very proud of him. >> reporter: 30-year-old patrick hamburger was a sergeant in the nebraska air national guard. he's survived by his fiance and 2-year-old daughter. and the next step for the families of the fallen is to wait for the bodies of their loved ones to be flown back here to american soil. carl? >> and as the nation tries to get over the shock of this attack is there any indication as to when the remains might be coming back state-side? >> it will be most likely in the next few days, probably this week. but so far military officials haven't released the full list of the names of the fallen. >> appreciate that. joining us tonight from norfolk, virginia. tensions are high in london, a day after the streets eruptsed in flames after a police protest spun out of control. authorities are breathing a sigh of relief as people appear to have heeded reports for calm. our report tonight from nbc's martin fletcher. >> reporter: london's worst riot in 30 years ended early this morning and at daybreak the clean-up began. fire destroyed this entire building, a carpet store. while 200 yards away, police detained another out, 48 arrested so far for sarsarson, looting, violence. atm machines were vandalized, shops looted in an all-night frenzy of destruction. this was a patrol car, police are hoping this will not be repeated tonight. but the young people are telling mere, they're going to destroy -- their word -- destroy two other areas nearby. this is what scares the police -- last night's out of control fury in tottenham high road in london. anger began growing thursday when police shot dead mark duggan, a 29-year-old father of four, who they described as a gangster. his friends doubted the police report, that he allegedly fired first at an officer. saturday night, duggan's friends and relatives protested outside the local police station. they say they did not want violence. but young thugs seized the moment. hurling rocks and bottles, a running battle with police. they torched two patrol cars, a double-decker bus and businesses and buildings. hundreds of thousands of dollars worst of goods stolen. but today, the parents of the dead man called for an end to the violence. apart from small outbreaks, their appeal appears to have worked. martin fletcher, nbc news, london. when "nightly news" continues this sunday, they can hack it. america's top spies infiltrate a conference of computer geeks in search of new recruits. and later, making a difference, a neighborhood filled with fast food joints and no healthy options, until one man's fresh idea rolled into town. in recent days, the computer-hacking group known as anonymous launched a cyberattack on u.s. law enforcement websites, posting a trove of private information online. as a growing worry in the u.s. that we're falling behind in the cyberbattle and you'll never guess where officials are looking for recruits to fight back. nbc's justice correspondent pete williams has our report. >> reporter: at this las vegas conference of computer geeks, the federal government is looking for hackers. but it's not trying to arrest them, it's trying to hire them. >> you're dealing with the brightest people in the world. these people come together here to exchange and share ideas. and we need those type of people. >> the national security agency, nsa, for decades the federal government's eavesdropper in chief, is scrambling to deploy more troops object the latest security battlefield. it's the real-life version of cyberattacks depicted on the tv series, "24" and the movie "die hard 4." hackers targeting the computers that control the stock market or the power grid. air traffic controls or phone networks. >> the adversary is everywhere. we are everyone's target. we will always have that bull's eye on our shirt. >> dickie george is the man in charge of the nsa's cyberdefenders, its directate for information assurance. he says the agency is looking to hire nearly 3,000 cyber experts in the next two years. and the computer whizes at places like that las vegas hacker convention are made to order. >> i solve problems extremely quickly and i enjoy learning, it's my passion in life and i think with that skill set, that would be valuable to anyone. >> we need them. there are too few people on our side right now. >> it's the cyber version of it takes a thief to catch a thief. nsa wants experts 40 can strengthen the nation's defenses, probe for weaknesses and detect attacks in their earliest stages. every day brings words that cyberthieves have stolen secrets from companies and a new report from a cybersecurity firm mcafee reports that all from a single source, widely thought to be china. >> the government's concern is state-sponsored espionage in an unprecedented scale. foreign governments targeting our nation's networks and the private-sector networks. and that's why the government is hiring so many new cyb cyber specialists. >> reporter: and giving so many computer hackers a chance to work for the good guys. up next, living in constant fear south of the border. violent week in the war next door. oh, we call it the bundler. let's say you need home and auto insurance. you give us your information once, online... [ whirring and beeping ] [ ding! ] and we give you a discount on both. sort of like two in one. how did you guys think of that? it just came to us. what? bundling and saving made easy. now, that's progressive. call or click today. is there a prize in there? oh, there's a prize, all right. is it a robot? no. is it a jet plane? nope. is it a dinosaur? [ laughs ] [ male announcer ] inside every box of heart healthy cheerios are those great tasting little o's made from carefully selected oats that can help lower cholesterol. stickers? uh-uh. a superhero? ♪ . . . . we want to show you these images of one of the world's most active volcanoes roaring once again. italy's mount aetna is putting on quite a show this weekend in sicily, spewing lava and ash into the night sky. it's been an especially bloody week south of the border in mexico's deadly war on drugs, ruthless cartels have stepped up violence in one city in particular, ambushing police and leaving everyone to live in constant fear. nbc's mark potter reports tonight on the war next door. >> reporter: just south of the u.s. border, mexico's vicious drug war is unrelenting. authorities say in the small town of ascension, gunmen working fon a drug cartel kidnapped and killed the police chief and murdered five of his 31 men. fearing they could be next, the town's remaining 26 officers turned in their guns and quit. leaving the town unprotected. within 48 hours of the defections, federal soilldiers were deployed to replace the local police in try to restore order in a town located in a drug-smuggling route. one told a mexican reporter that mexico's war against drugs is not being won. >> probably the weakest part of president felipe calderon's war against drugs is his failure to prosecute. >> the presidency of felipe calderon under pressure to demonstrate that it's winning the war against carsles paraded captured drug lords in front of the cameras. this man called el diego is described as one of the biggest catches of all. one of the most wanted men in mexico. where authorities claim he has now confessed to mastderminding 1500 killings in juarez, mexico's murder capital. despite the high-profile arrest savage gang violence claimed at least nine new victims this weekend. >> the only thing that will stop them is themselves. become so viral that they'll kill themselves off. but in the process, many, many innocent people will be killed. >> it's a war that has now claimed 40,000 lives in the last five years. mark potter, nbc news, miami. >> well what was once tropical storm emily dumped heavy rains in the bahamas this weekend and it's now moving northeast and dissipating. posing no threat to land. when we come back, a fresh start for a neighborhood that could really use one. finally tonight, in many cities across the country there's something that's especially hard to find -- a supermarket selling fresh food. and experts say these so-called food deserts are a serious health issue. in chicago, one innovative idea is making a difference, we get our report tonight from nbc's john yang. >> reporter: in this gritty neighborhood on chicago's west side, fresh fruits and vegetables take the bus. >> what did you get today? >> i got greens. >> reporter: can you show us? look at those greens. >> i got a honeydew mellon and green tomatoes. >> reporter: this retired chicago transit bus stops here once a week. a produce market on wheels selling items often hard to come by in urban neighborhood ace cross the country. liquor stores and convenience stores dot the street selling processed foods that may not provide the healthiest of diets. >> what you can't find is an affordable, quality set of fruits and vegetables in these communities on a 365-day basis. >> reporter: supermarkets are miles away. studies estimate that 31 million americans live in these so-called food deserts. >> residents of a food desert are more likely to die and suffer prematurely from diet-related conditions such as diabetes, certain kinds of cancers, actually cardiovascular disease. >> reporter: steven casey lives in a food desert, but he has a car. for those who don't, he decided if people can't get to the fresh food, he would find a way to take it to them. >> woe have watermelon, bananas. >> it's a civil right that i ought to be able to eat healthy. and that if i have it on the north side or a near west side or near south side or downtown, why can't i have it over here? >> reporter: so he helped start fresh moves, after spending four years raising money, the group bought a bus from the chicago transit authority for $1. and then spent $50,000 repairing it and turning it into a produce section on wheels. twice a week it loads up with fresh fruits and vegetables and visits six different sites on chicago's west side. for delors varney, it's a reminder of the days there was plenty of fresh food on sale in this neighborhood. >> that's been years ago. >> reporter: a day that organizers hope this bus will deliver to more and more neighborhoods year-round, john yang, nbc news, chicago. and that's "nbc nightly news" for this sunday. brian williams will be here tomorrow, i'm carl quintanilla reporting from new york. for lester holt and all of us here at nbc news, thanks for watching. here at nbc news, thanks for watching. good night. captions paid for by nbc-universal television