British Prime Minister David Cameron has recalled parliament from its summer recess and nearly tripled the number of police on the streets to deal with the crisis.
Cameron cut short a vacation in Italy and rushed back to London to deal with some of the city's worst rioting in years. Buildings, cars and bus stops burned and police fought with young people for a third straight night Monday in several London neighborhoods.
After viewing the destruction, the prime minister described the burned-out, ransacked buildings as "sickening."
Cameron says the police will swell their ranks from 6,000 to 16,000 in London Tuesday. And in a surprise move, Britain's Wednesday football match with the Netherlands was canceled.
Violence has also broken out in at least three other British cities, with police in Birmingham, Liverpool and Bristol reporting fires and looting.
The violence broke out in London after police shot to death a 29-year-old man in the economically depressed Tottenham neighborhood late last week.
A peaceful demonstration marking his death exploded into violence Saturday when protesters threw stones at police, smashed store windows, and set cars and buses on fire.
Many London residents say the riots were spurred by anger over the gloomy economic situation in north London, including high unemployment and reduced public services.
Police say they have so far arrested more than 450 people and charged 69 with offenses. A total of 35 officers have been hurt, including three policemen run over by a car while trying to make arrests.
British Deputy Prime Minister Nick Clegg called the violence "needless," "opportunistic" and "completely unacceptable." Home Secretary Theresa May condemned the rioters as criminals.
Tottenham is home to a large number of ethnic minorities and has a history of racial tensions. In 1985, a police officer was hacked to death there when Afro-Caribbean youths in a deprived housing estate went on a rampage.