LONDON (AP) -- Prime Minister David Cameron said Thursday that Britain would look to the United States for solutions to gang violence after nights of riots and looting, and promised authorities would get strong powers to stop street mayhem erupting again.

Cameron told lawmakers he was "acting decisively to restore order on our streets," as police raided houses to round up suspects from four nights of unrest in London and other English cities.

Acknowledging that police had been overwhelmed by mobile groups of looters in the first nights of the rioting, Cameron said authorities were considering new powers, including allowing police to order thugs to remove masks or hoods, evicting troublemakers from subsidized housing and temporarily disabling cell phone instant messaging services.

He said the 16,000 police deployed on London's streets to deter rioters and reassure residents would remain through the weekend.

"We will not let a violent few beat us," Cameron said.

Lawmakers were summoned back from their summer vacations for an emergency session of Parliament on the riots as government and police worked to regain control, both on the streets and in the court of public opinion. Calm prevailed in London overnight, with a highly visible police presence watching over the capital, but a sense of nervousness lingered across the country.

During a session lasting almost three hours in which he faced 160 questions from lawmakers, Cameron promised tough measures to stop further violence and said "nothing should be off the table." He said that included water cannon and plastic bullets - though senior police have said they don't feel the need to use those at the moment. He also said officials would look at "whether there are tasks that the army could undertake that would free up more police for the front line."

Cameron said he would seek American advice on fighting the street gangs he blamed for helping spark Britain's riots.

Cameron told lawmakers that he would look to cities like Boston for inspiration, and mentioned former Los Angeles and New York Police Chief Bill Bratton as a person who could help offer advice.

He said he wanted to look at cities that had fought gangs "by engaging the police, the voluntary sector and local government."

"I also believe we should be looking beyond our shores to learn the lessons from others who have faced similar problems," Cameron said.

He said the government, police and intelligence services were looking at whether there should be limits on the use of social media sites like Twitter and Facebook or services like BlackBerry Messenger to spread disorder.

BlackBerry's simple and largely cost free messaging service was used by rioters to coordinate their activities, Cameron's office said.

Government officials said they were discussing with spy agencies and communications companies whether messaging services could be disabled in specific areas, or at specific times.

Authorities are considering "whether it would be right to stop people communicating via these websites and services when we know they are plotting violence, disorder and criminality," Cameron said.

Cameron said that, in the future, police would be able to order people to remove masks, hoods or other face coverings when they suspect them of concealing their identity to carry out a crime. Currently, police must seek approval from a senior officer.

A program that can ban gang members from meeting together, loitering in certain places, or displaying gang insignia will also be extended, he said.

Some lawmakers urged Cameron to take even tougher measures. Conservative Party lawmaker Peter Tapsell said he recalled law enforcement officers in Washington D.C. in 1971 rounding up anti-Vietnam war demonstrators and imprisoning them in a sports stadium. Tapsell asked Cameron if London's Wembley Stadium, the country's showpiece soccer arena, could be used. Cameron insisted the stadium would be used only for "great sporting events."

Britain's riots began Saturday when an initially peaceful protest over a police shooting in north London turned violent. That clash triggered wider lawlessness that police struggled to halt.

Across London, and then in cities throughout England, rioters set stores on fire and looted shops for sneakers, bicycles, electronics and leather goods. For the first couple of nights there were too few police on the streets to challenge them.

That changed Tuesday, when 16,000 officers were deployed on London's streets - almost three times the number of the night before.

Police swooped on houses across London Thursday, detaining suspects and retrieving stolen goods. The number of people arrested since Saturday rose to 922, with 401 suspects charged.

Wednesday night was largely quiet in London and other cities where looters had rampaged earlier this week.

Tensions flared in Birmingham, where a murder probe was opened after three men were killed in a hit-and-run incident as they took to the streets to defend shops from looting.

Police on Thursday were given more time to question a 32-year-old man arrested on suspicion of murder.

Scenes of ransacked stores, torched cars and blackened buildings have frightened and outraged Britons just a year before their country is to host next summer's Olympic Games, bringing demands for a tougher response from law enforcement and calls for the government to scrap plans to cut police budgets.

Cameron's Conservative-led government is slashing 80 billion pounds ($130 billion) from public spending by 2015 to reduce the country's swollen budget deficit - measures that include curbing police budgets. A report last month said the cuts will mean 16,000 fewer police officers by 2015.

Normality was being restored in London Thursday, although soccer authorities announced that Tottenham Hotspur's season-opening match against Everton on Saturday was being postponed.

Nine other Premier League matches due to be played this weekend across the country are due to go ahead.

As authorities atempted to dispense swift justice to rioters, there were chaotic scenes at courthouses, several of which sat through the night to process scores of alleged looters and vandals, including an 11-year-old boy.

The defendants, mostly young but otherwise diverse, included a teenage ballerina, a university English student from a prosperous commuter town and Natasha Reid, a 24-year-old university graduate who admitted stealing a TV from a looted electronics store in north London. Her lawyer said she had turned herself in because she could not sleep because of guilt.

Also due to appear in court were several people charged with using Twitter and Facebook to incite violence.

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David Stringer in London and Shawn Pogatchnik in Birmingham, England contributed to this report.

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