Scenes of ransacked stores, torched cars and blackened buildings frightened and outraged Britons just a year before London is to host the summer Olympic Games, and brought demands for a tougher response from law enforcement.
London's Metropolitan Police department put thousands more officers in the streets and said that by Wednesday there would be 16,000 - almost triple the number present Monday. Dozens of police were seen combing through the Canning Town area of east London as officers hunted for potential new flash points, but the department acknowledged it could not guarantee an end to the violence.
Though London saw no new unrest late Tuesday, but the chaos spread to other cities. A police station in the central England city of Nottingham was firebombed by a 40-strong mob, and hundreds of youths battled police in the northwestern city of Manchester.
Stores, offices and nursery schools across London closed early amid fears of fresh rioting. Many usually busy streets had an eerie calm as cafes, restaurants and pubs also decided to shut down for the night.
Many shops had their metal blinds pulled down, while other business owners rushed to secure plywood over their windows before nightfall.
Some London residents prepared to defend their homes and stores. Outside a Sikh temple in Southall, west London, residents stood guard and 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.
In east London's Bethnal Green district, convenience store owner Adnan Butt, 28, said residents were tense.
"People are all at home - they're scared" of the rioters, he said.
London's deputy assistant police commissioner Steve Kavanagh vowed that large numbers of officers would remain on London's streets until calm was restored.
"We will continue with this additional policing for as long as is necessary. Our priority remains protecting the public and restoring order to our streets," he said.
In Nottingham, police said rioters had hurled firebombs though the window of a police station in the Canning Circus area of the city, but that there were no reports of injures. Eight men were arrested at the scene, where firefighters doused a blaze.
In 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. Looters targeted stores selling designer clothes and expensive consumer electronics.
Neither Manchester nor Nottingham had previously been involved in unrest. There also was minor unrest for the first time in the central England locations of Leicester, Wolverhampton and West Bromwich.
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 with ordinary tactics. While the rioters have run off with sneakers, bikes, electronics and leather goods, they also have torched stores apparently just for the fun of seeing something burn.
Rioters, able to move quickly and regroup to avoid the police, have been left virtually unchallenged in several neighborhoods, plundering stores at will.
Police said they were considering the use of plastic bullets - blunt-nosed projectiles designed to deal punishing blows to rioters without penetrating the skin. Such weapons, formally called baton rounds, still are used to quell riots in Northern Ireland but have never been used by police on Britain's mainland.
The government rejected calls by Conservative lawmaker Patrick Mercer and some members of the public for strong-arm riot measures that British police generally avoid, such as tear gas and water cannons.
"They should have the tools available and they should use them if the commander on the ground thinks it's necessary," Mercer said.
Police did offer advice on what actions people could legally take to defend homes from attack. "As a general rule, the more extreme the circumstances and the fear felt, the more force you can lawfully use in self-defense," London's police department said in advice circulated late Tuesday.
In central England, police said they had made five new arrests amid violence Tuesday in Birmingham - which also suffered rioting on Monday - and had dispersed a small group of people who torched two cars in the center of West Bromwich, a nearby town. About 20 people were arrested following rioting in the central city of Wolverhampton, police said.
Riots and looting has flared across London from gritty suburbs along the capital's fringes to the posh Notting Hill neighborhood. The disorder has caused heartache for Londoners whose businesses and homes were torched or ransacked, and a crisis for police and politicians already staggering from a spluttering economy and a scandal over illegal phone hacking by a tabloid newspaper that has dragged in senior politicians and police.
"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.
So far more than 560 people have been arrested in London and about 100 charged - including an 11-year-old boy - and the capital's prison cells were overflowing. Several dozen more were arrested in other cities. The Crown Prosecution Service said it had teams of lawyers working 24 hours a day to help police decide whether to charge suspects.
Silke said it will be hard to control the rioting until police make larger numbers of arrests.
"People are seeing images of lines of police literally running away from rioters," he said. "For young people that is incredibly empowering. They are breaking the rules. They are getting away with it. No one is able to stop them."
The unrest has been Britain's worst since race riots set the capital ablaze in the 1980s. "No one should wake in this wonderful city of ours to see such scenes of devastation and violence," Kavanagh said early Tuesday, as police and lawmakers surveyed the damage.
London's beleaguered police force noted that it had received more than 20,000 emergency calls on Monday - four times the normal number. Scotland Yard has called in reinforcements from around the country and asked all volunteer special constables to report for duty.
A soccer match scheduled for Wednesday between England and the Netherlands at London's Wembley stadium was canceled to free up police officers for riot duty. Britain's soccer authorities said they were in talks with police to see whether this weekend's season-opening matches of the Premier League could still go ahead in London.
Police launched a murder inquiry after a man found with a gunshot wound during riots in the south London suburb of Croydon died of his injuries Tuesday, and arrested three people on suspicion of the attempted murder of a police officer hit by a car.
A total of 111 officers and 14 members of the public had been hurt so far in the rioting, including a man in his 60s with life-threatening injuries, police said.
Prime Minister David Cameron - who cut short a holiday in Italy to deal with the crisis, reversing an earlier decision to remain on his vacation - recalled Parliament from its summer recess for an emergency debate Thursday on the riots. He described the scenes of burning buildings and smashed windows as "sickening," but refrained from tougher measures such as calling in the military to help restore order.
"People should be in no doubt that we will do everything necessary to restore order to Britain's streets and to make them safe for the law-abiding," Cameron told reporters after a crisis meeting at his Downing Street office.
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 - who flew back overnight from his summer vacation - 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 Olympics.
"We have time in the next 12 months to rebuild, to repair the damage that has been done," he said. "I'm not saying it will be done overnight, but this is what we are going to do."
Violence broke out late Saturday in the low-income, multiethnic district of Tottenham in north London, after a protest against the fatal police shooting of Mark Duggan, a 29-year-old father of four who was gunned down in disputed circumstances Thursday.
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.
The Independent Police Complaints Commission, which is investigating the shooting, said a "non-police firearm" was recovered at the scene, but that there was no evidence it had been fired - a revelation that could fuel the anger of the local community.
An inquest into Duggan's death was opened Tuesday, though it will likely be several months before a full hearing.
Duggan's death stirred memories of the 1980s, when many black Londoners felt they were disproportionately stopped and searched by police. The frustration erupted in violent riots in 1985, during which a police officer was stabbed to death.
Relations have improved since then, but tensions remain and many young people of all races mistrust the police.
Seeking explanations for the unrest, some pointed to rising social tensions in Britain as the government slashes 80 billion pounds ($130 billion) from public spending by 2015 to reduce the country's huge budget deficit, swollen after the country spent billions bailing out its foundering banks.
But many rioters appeared simply to relish the opportunity for unchecked violence Monday night. "Come join the fun!" shouted one youth as looters hit the east London suburb of Hackney.
In Croydon, fire gutted a 140-year-old family run department store, House of Reeves, and forced nearby homes to be evacuated. "No one's stolen anything," said owner Graham Reeves, 52. "They just burnt it down."
Many Londoners emerged on Tuesday with brooms to help sweep the streets of broken glass, rallying to the aid of those whose homes or premises had been vandalized.
The riots could not have come at a worse time for police - a year before the Olympic Games, which Scotland Yard says will be the biggest challenge in its 182-year history.
Cameron's government has slashed police budgets under its austerity program. A report last month by Her Majesty's Inspectorate of Constabulary said the cuts - a third of which have already taken place - will mean 16,000 fewer police officers by 2015.
Scotland Yard is also without a full-time leader after chief Paul Stephenson quit last month amid a scandal over the ties between senior officers and Rupert Murdoch's British newspapers, which are being investigated for hacking phone voicemails and bribing police for information. The force's top counterterrorism officer, John Yates, also quit over the hacking scandal.
Jill Lawless, Danica Kirka, Meera Selva, Sheila Norman-Culp and Stephen Wilson contributed to this report.