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," the prime minister 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 on Wednesday night, 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 officers 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.
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.
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.
