Thousands of extra police officers on the streets kept a nervous London quiet Wednesday after three nights of rioting, but looting flared in Manchester and Birmingham, where a murder probe was opened when three men were killed after being hit by a car.
An eerie calm prevailed in the capital, where hundreds of shops were shuttered or boarded up as a precaution, but unrest spread across England on a fourth night of violence by brazen crowds of young people.
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. Police across the country have made almost 1,200 arrests since the violence broke out over the weekend.
In London, where armored vehicles and convoys of police vans patrolled the streets, authorities said there were 16,000 officers on duty -- almost triple the number present Monday night.
The show of force seems to have worked. There were no reports of major trouble in London, although there were scores of arrests. Almost 800 people have been arrested in London since trouble began Saturday.
"What happened in London last night was, when community leaders and the police came together, there were significant arrests," said police deputy assistant chief constable Stephen Kavanagh. "We used buses to make sure some looters were taken away before they got into doing anything, but it was that joint action that made the difference."
Outside the capital, some looting erupted, but not on the scale of the violence that hit several areas of London on Monday.
In the northwestern city of Manchester, hundreds of youths rampaged through the city center, hurling bottles and stones at police and vandalizing stores. A women's clothing store on the city's main shopping street was set ablaze, along with a disused library in nearby Salford.
Manchester assistant chief constable Garry Shewan said it was simple lawlessness.
"We want to make it absolutely clear -- they have nothing to protest against," he said. "There is nothing in a sense of injustice and there has been no spark that has led to this."
Britain's soccer authorities were talking with police to see whether this weekend's season-opening matches of the Premier League could still go ahead in London. A Wednesday match between England and the Netherlands at London's Wembley stadium was canceled to free up police officers for riot duty.
Britain's riots began Saturday when an initially peaceful protest over a police shooting in London's Tottenham neighborhood turned violent. That clash has morphed into a general lawlessness in London and several other cities that police have struggled to halt.
While the rioters have run off with goods every teen wants -- new sneakers, bikes, electronics and leather goods -- they also have torched stores apparently just for the fun of seeing something burn. They were left virtually unchallenged in several neighborhoods, and when police did arrive they often were able to flee quickly and regroup.
With police struggling, some residents stood guard to protect their neighborhoods. Outside a Sikh temple in Southall, west London, residents vowed to defend their place of worship if mobs of young rioters appeared. Another group marched through Enfield, in north London, aiming to deter looters.
One far-right group said about 1,000 of its members were taking to the streets to deter rioters.
"We're going to stop the riots -- police obviously can't handle it," Stephen Lennon, leader of the far-right English Defense League, told The Associated Press. He warned that he couldn't guarantee there wouldn't be violent clashes with rioting youths.
Anders Behring Breivik, who has confessed to the bombing and massacre that killed 77 people in Norway last month, has cited the EDL as an inspiration.
In the central England city of Nottingham, police said rioters hurled firebombs though the window of a police station, and set fire to a school and a vehicle but there were no reports of injuries. Some 90 people were arrested.
Some 250 people were arrested after two days of violence in Birmingham -- where police launched a murder investigation after the deaths of three men hit by a car -- some residents said the men had been patrolling their neighborhood to keep it safe from looters.
Police said a man had been arrested on suspicion of murder in the case.
In the northern city of Liverpool, about 200 youths hurled missiles at police and firefighters in a second night of unrest, and 44 arrests were reported.
There also were minor clashes in the central and western England locations of Leicester, Wolverhampton, West Bromwich, Bristol, and Gloucester -- where police and firefighters tackled a blaze and disturbance in the city's Brunswick district.
In London, hundreds of stores, offices, pubs and restaurants had closed early Tuesday amid fears of fresh rioting. Normally busy streets were eerily quiet and the smell of plywood filled the air as business owners rushed to secure their shops before nightfall.
In east London's Bethnal Green district, convenience store owner Adnan Butt, 28, said the situation was still tense.
"People are all at home -- they're scared," he said.
Prime Minister David Cameron's government rejected calls by some lawmakers and citizens for strong-arm riot measures that British police generally avoid, such as tear gas and water cannons.
"The public wanted to see tough action. They wanted to see it sooner and there is a degree of frustration," said Andrew Silke, head of the criminology department at the University of East London.
Cameron recalled Parliament from its summer recess for an emergency debate on the riots Thursday.
Other politicians visited riot sites Tuesday -- but for many residents it was too little, too late. Deputy Prime Minister Nick Clegg was booed by crowds who shouted "Go home!" in Birmingham, while London Mayor Boris Johnson was heckled on a shattered shopping street in Clapham, south London.
Johnson said the riots would not stop London from "welcoming the world to our city" for the 2012 Olympics.
So far 770 people have been arrested in London and 167 charged -- including an 11-year-old boy -- and the capital's prison cells were overflowing. Britain's Crown Prosecution Service said it had teams of lawyers working 24 hours a day to help police decide whether to charge suspects.
A total of 111 officers and 14 members of the public have been hurt.
The violence was triggered by the fatal police shooting of Mark Duggan, a 29-year-old father of four who was gunned down in Tottenham on Thursday under disputed circumstances.
Police said Duggan was shot dead when officers from Operation Trident -- the unit that investigates gun crime in the black community -- stopped a cab he was riding in. A Saturday protest demanding justice degenerated into a riot, which spread to neighboring parts of London on Sunday and by Monday had spread across the capital.
Duggan's death resonated because it stirred memories of the 1980s, when many black Londoners felt they were disproportionately stopped and searched by police. Their frustration erupted in violent riots in 1985.
But the rioters who have taken to the streets since Sunday have been extremely diverse -- those in central England appeared to be mostly white and working class.
Paisley Dodds, Jill Lawless, Danica Kirka and Meera Selva contributed to this report.