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Residents surveyed shattered streets and police vowed a wave of arrests Monday after riots and looting erupted in an impoverished London neighborhood and hopscotched across the city that hosts next summer's Olympic Games.

The unrest was sparked by a police shooting, but some blamed unemployment, insensitive policing and opportunistic looting for the worst violence the city has seen in years. Police and politicians insisted the disorder was the work of a criminal minority and not a sign of social tensions or security lapses ahead of the 2012 Games.

In the hardest-hit area, Tottenham, many residents agreed that the looting was the work of greedy youths, aided by instant communication through SMS texts and instant messaging.

"It's nothing to do with the man who was shot, is it?" said 37-year-old Marcia Simmons, who has lived in the diverse and gritty north London neighborhood all her life. "A lot of youths ... heard there was a protest and joined in. Others used it as an opportunity to kit themselves out, didn't they, with shoes and T-shirts and everything."

Scattered violence continued Monday, with a skirmish breaking out between police and groups of youths in the Hackney area of east London. Several youths attacked shops and windows, and police in riot gear were pelted wth pieces of wood and other objects.

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Tottenham's main shopping street remained cordoned off, with steam still rising from burnt-out buildings two days after violence broke out amid community anger over a fatal police shooting.

Mark Duggan, a 29-year-old father of four, was gunned down in disputed circumstances Thursday in Tottenham.

A peaceful demonstration outside the Tottenham police station turned ugly as several hundred people threw bottles filled with gasoline at police lines and confronted officers with baseball bats and bars. Two police cars and a double-decker bus were set alight, stores were looted and several buildings along Tottenham's main street -- five miles (eight kilometers) from the site of the 2012 Olympics -- were reduced to smoldering shells.

"I saw cars on fire, and the neighbors came out saying there's a full blown riot," Simmons said.

"We saw the bus set alight, and we saw it blow up. All our homes were full of smoke."
Police condemned the "copycat criminal" violence that started Sunday and hit areas including the leafy suburb of Enfield, a few miles (kilometers) further north; Walthamstow in northeast London, where police said 30 youths vandalized and looted shops; and the busy shopping and tourist district at Oxford Circus, where about 50 people damaged property.

British Home Secretary says 215 people have been arrested  while police said 35 police officers were injured.

"This has changed from a local issue into organized criminality," police deputy assistant commissioner Steve Kavanagh said Monday as he announced a "momentous investigation" to track down the perpetrators.

"We will make sure that this criminality is not allowed to continue," Kavanagh told Sky News.

The perpetrators were relatively small groups of youths -- their heads and faces covered -- who used social media such as Twitter, mobile phone text messages and instant messaging on BlackBerrys to organize and keep a step ahead of police. One BlackBerry message Sunday, whose authenticity could not be verified, urged young people from across London to converge on Oxford Circus for "pure terror and havoc & free stuff."

Once the preserve of businesspeople, BlackBerry handsets are popular with teenagers thanks to their free, fast instant messaging system.

Blackberry's manufacturer, Research in Motion, said in a statement: "We feel for those impacted by the riots in London. We have engaged with the authorities to assist in any way we can."

Police said they would be monitoring Twitter feeds and those who incited violence could face arrest.

In the south London neighborhood of Brixton -- the scene of riots in the 1980s and 1990s -- youths smashed windows, attacked a police car, set fire to garbage bins and stole video games, sportswear and other goods from stores on Sunday night.

Like Brixton, Tottenham is an impoverished area with an ethnically diverse population, a large black community and a history of unrest. Tottenham was the site of the 1985 Broadwater Farm riots, a series of clashes that led to the fatal stabbing of a police officer and the wounding of nearly 60 others -- and underscored tensions between London police and the capital's black community.

Since then police have made concerted, and fairly successful, efforts to build better relations with London's ethnic communities. But mistrust still lingers, and the shooting of Duggan -- a popular figure in the community -- has stirred old animosities.

Few details of Duggan's death have been released, and in the void rumors have swirled.
Police say Duggan was shot dead when police from Operation Trident -- the unit that investigates gun crime in the black community -- stopped a cab he was riding in.

The Independent Police Complaints Commission, which is investigating the shooting, said a "non-police firearm" was recovered at the scene, and media reports said a bullet had been found in an officer's radio.

But the Guardian newspaper reported that the bullet in the radio was police-issue, indicating Duggan may not have fired at the officer.

Duggan's family said they did not condone the violence, and politicians condemned attempts to use his death as an excuse for the riots.

"The violence we saw last night had absolutely nothing to do with the death of Mr. Duggan," said Deputy Prime Minister Nick Clegg.

There are signs of rising social tensions in Britain as the government slashes 80 billion pounds ($130 billion) from public spending by 2015 to reduce the huge deficit, swollen after Britain spent billions bailing out its foundering banks.

The past year has seen mass protests against the tripling of student tuition fees and cuts to public sector pensions. In November, December and March, small groups broke away from large marches in London to loot. In the most notorious episode, rioters attacked a Rolls-Royce carrying Prince Charles and his wife Camilla to a charity concert.

The full impact of spending cuts has yet to be felt, however, and the unemployment rate is stable -- although it highest among youth, especially in areas like Tottenham.

Many locals dismissed socio-economic explanations for the riots.

"We are going to get people blaming the economy and what happened last week but that's not the real reason this happened," said Brixton resident Marilyn Moseley, 49. "It's just an excuse for the young ones to come and rob shops."

The riots caught British politicians by surprise. Many, including Prime Minister David Cameron, were on vacation abroad when they broke out. Cameron's office said he had no plans to return early, although Home Secretary Theresa May flew back from vacation Monday for talks with police chiefs.

London Mayor Boris Johnson was criticized for not returning from his own holiday, although he did condemn the "utterly appalling" destruction.

"People have lost their homes, businesses and livelihoods through mindless violence," he said in a statement.

For civic leaders and Olympic organizers, the violence was an unwelcome reminder of London's volatility, less than a year before the city hosts the 2012 Games.

The International Olympic Committee said it had confidence in British authorities.

"Security at the Olympic Games is a top priority for the IOC," spokesman Mark Adams said. "It is, however, directly handled by the local authorities, as they know best what is appropriate and proportionate. We are confident they will do a good job in this domain."

Images of buildings and vehicles in flames broadcast around the world were poor publicity for the city as it prepares to host the games.

"You can imagine how stretched the police would be if this were to occur during the Olympics," said Tony Travers, a local government expert at the London School of Economics. "So I think this will create a worry within City Hall and the Home Office.

"It's not so much that this might happen again -- unlikely -- as that it reminds the people in charge that while the Olympic Games are going on, any other major event is going to be complicated."

Senior politicians, including Clegg, visited Tottenham on Monday in a bid to reassure residents.

But many despaired for the future of their community.

"We are the ones who have to live here now," said Simmons. "My son was terrified. He slept in my bed."

She wondered how Tottenham would recover.

"The High Road wasn't great, but it was O.K. I'm thinking it will be like a ghost town now. Why would anyone want to open a business here?" Simmons asked.