LONDON - British police on Monday promised a "momentous operation" to arrest rioters after a weekend of vandalism and looting that erupted in a disadvantaged London neighborhood just miles (kilometers) from the site of next year's Olympic Games.

A police officer keeps pedestrians from crossing into a crime scene after overnight looting in Brixton, south London August 8, 2011. British police arrested more than 100 people overnight in London after shops were looted and officers attacked in a second night of violence that followed some of the worst disorder seen in the capital for years.[Photo/Agencies]

Groups of masked and hooded young people looted shops, attacked police officers and set fire to vehicles in violence that has raised questions about security ahead of the 2012 Olympics and revealed pent-up anger against the city's police. Over 160 people were arrested.

Around 35 police officers were injured, including three hit by a car while trying to make arrests in northeast London. Police commander Christine Jones said officers were "shocked at the outrageous level of violence directed against them."

"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 violence broke out in the gritty north London suburb of Tottenham on Saturday night amid community anger over a fatal police shooting of a 29-year-old father of four. Police said "copycat criminal" violence spread to other parts of the city Sunday night and early Monday, including, briefly, London's busy shopping and tourist district at Oxford Circus.

The protest over the death of Mark Duggan, who was gunned down in disputed circumstances Thursday, was initially peaceful. But it turned ugly as up to 500 people gathered around Tottenham's police station late Saturday.

Some protesters threw bottles with gasoline at police lines while others confronted officers with baseball bats and bars and attempted to storm the station. Two police cars and a double-decker bus were set alight, and several buildings along Tottenham's main street were set alight and reduced to smoldering shells.

Tottenham was quiet on Sunday night, but looting spread to the leafy suburb of Enfield, a few miles (kilometers) further north, and to Walthamstow in northeast London, where, police said 30 youths vandalized and looted shops. Another 50 people damaged property at Oxford Circus in the city center.

Tottenham is five miles (8 kilometers) from the Olympic site and Walthamstow is only three miles (5 kilometers) away.

In the south London neighborhood of Brixton _ the scene of riots in the 1980s and 90s _ youths on Sunday night smashed windows, attacked a police car, set fire to garbage bins and stole video games, sportswear and other goods from stores.

"It's obviously stemmed from what's happened in Tottenham, but we are 10 miles away," said Williams Falade, manager of a gym that was closed Monday because the restaurant next door had been attacked. "It was like it was an excuse. Things like this will happen, but they should happen for better reasons."

Tottenham has a history of unrest. It was the site of the 1985 Broadwater Farm riots, a series of clashes that led to the savage stabbing of a police officer and the wounding of nearly 60 others _ underscoring tensions between London police and the capital's black community.

Relations have improved but mistrust still lingers, and the shooting of Duggan _ a popular figure in the community _ has stirred old animosities.

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.

"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."

Very few details of Duggan's death have been released, although police said initially an officer was briefly hospitalized after the shooting. Media reports said a bullet had been found lodged in the officer's radio.

In a bid to calm rumors, the Independent Police Complaints Commission, which is investigating the shooting, released a statement saying "speculation that Mark Duggan was 'assassinated' in an execution-style involving a number of shots to the head are categorically untrue." It also said a "non-police firearm" was recovered at the scene.

But the circumstances of his death remain unclear.

Although a gun was recovered from the scene, The Guardian newspaper reported that the bullet in the radio was police-issue, indicating Duggan may not have fired at the officer.

With images of buildings and vehicles in flames broadcast around the world, London Mayor Boris Johnson was criticized for not returning from vacation after Saturday's riot.

Kit Malthouse, the deputy mayor for policing in London, defended his boss.

"Should he be reacting to these criminal provocateurs in that way by coming back? I think that is kind of rewarding them," he told Sky News. "Modern communications mean he can stay in touch and participate in meetings from around the globe."