Eight police officers were being treated in hospital today following riots which broke out two days after a man was shot dead by police.
Scotland Yard said at least one of the officers had suffered head injuries after protesters clashed with police in Tottenham, north London.
Trouble flared after members of the community took to the streets last night to demand "justice", after Mark Duggan, 29, was shot dead by police on Thursday.
The riots saw buildings and vehicles set alight, including two patrol cars, a police van and a double-decker bus, and shops looted as police in riot gear arrived on the scene.
Hundreds of people gathered in the street, including mounted police, as smoke poured into the air from the lighted bus.
Fire engines descended on the area and thunderflashes were thrown at police on horseback.
After sections of Tottenham High Road were cleared of protesters, "pockets of trouble" continued to flare in nearby areas, a Scotland Yard spokesman said.
Two vans were reported to have been set ablaze in nearby Rheola Close, and Sky News said that its reporter and cameraman had to withdraw from the area over safety fears.
There were also reports of looting in Tottenham Hale Retail Park.
A spokeswoman for London Ambulance Service said paramedics had treated 10 people, and nine were taken to hospital.
The violence erupted after around 120 people marched from the local Broadwater Farm area to Tottenham police station yesterday, forcing officers to close the High Road and put traffic diversions in place.
After night fell, two police cars parked about 200 yards from the police station were set upon.
Scotland Yard said in a statement: "Two police cars had parked up at Forster Road/ High Road while their officers conducted traffic patrols on foot. This is about 200 yards north of Tottenham Police Station.
"At approximately 8.20pm a number of bottles were thrown at these two cars. One was set alight and the second was pushed into the middle of the High Road. It was subsequently set alight.
"The officers were not in the vehicles and were unhurt.
"Officers from the Territorial Support Group have been deployed to disperse the crowd. They are deployed to the north and south of Tottenham Police Station in the High Road, and are subject to bottles and other missiles being thrown at them by the crowd."
A family friend of Mr Duggan, who gave her name only as Nikki, 53, said the man's friends and relatives had organised the protest because "something has to be done" and the marchers wanted "justice for the family."
Some of those involved lay in the road to make their point, she said.
"They're making their presence known because people are not happy," she added. "This guy was not violent. Yes, he was involved in things but he was not an aggressive person. He had never hurt anyone."
As the scenes of violence escalated, local MP David Lammy appealed for calm, saying in a statement that the events were "not representative of the vast majority of people in Tottenham".
He added: "Those who remember the destructive conflicts of the past will be determined not to go back to them.
"We already have one grieving family in our community and further violence will not heal that pain.
"True justice can only follow a thorough investigation of the facts.
"The Tottenham community and Mark Duggan's family and friends need to understand what happened on Thursday evening when Mark lost his life. To understand those facts, we must have calm."
A spokesman for the Mayor of London Boris Johnson urged those involved in the violence to "respect the rule of the law", adding that "violence and destruction of property will do nothing to facilitate this investigation".
Commander Stephen Watson of the Metropolitan Police, which has set up a gold command room in Lambeth to oversee the incident, stressed that "a significant number of police officers" had been deployed to the scene, telling BBC News: "Our people are very well trained and led. We are exercising contingency plans which are well rehearsed."
He added: "Our intention is to restore calm and normality to the area as soon as possible."
He said there would be arrests for criminal offences, but that they came second to preserving public safety.
Commissioner Rachel Cerfontyne, of the Independent Police Complaints Commission (IPCC), said in a statement: "I understand the distress that the shooting of Mark Duggan has caused to his family and in the community and that people need answers about what happened to him."
She said the IPCC yesterday supported 14 family members and friends in formally identifying Mr Duggan's body, and would have further meetings with his family today.
"We are still gathering evidence and will release further details about our progress with the investigation as soon as we can."
On Friday, it emerged that Mr Duggan had been travelling in a minicab and was gunned down after an apparent exchange of fire.
A police officer's radio was found to have a bullet lodged in it afterwards, suggesting they may have narrowly escaped being struck.
Officers had been attempting to carry out an arrest under the Trident operational command unit, which deals with gun crime in the black community, according to the IPCC.
Last night's troubles evoked memories of 1985, when a police officer, Pc Keith Blakelock, was hacked to death following a riot in Broadwater Farm, where the marchers set off yesterday.
Scotland Yard said this morning: "There remain isolated pockets of criminality in the Tottenham area involving a small number of people. Officers are currently taking steps to deal with these incidents."
In a statement, Commander Watson described the scenes of violence as "distressing" for Londoners and the local community, and stressed that the safe of the public was "of paramount importance to us".
He added: "We did not have warnings that we were going to see the kind of disorder being witnessed tonight.
"We are aware of raised tensions in the community, which are understandable following the tragic death of Mark Duggan.
"What we experienced earlier on yesterday evening was a peaceful protest outside Tottenham police station - there was no indication it would deteriorate in this way.
"For those who involved themselves in this level of violence, there is no excuse."
A spokesman for the London Fire Brigade said: "At the moment all the fires are under control. We are still at the scene of some of them to damp them down and make sure everything is out."
Buildings including a supermarket and a carpet shop were set alight during the disturbances.
Stuart Radose had to flee his flat above a Carpetright shop last night as a fire ravaged the building.
Describing the scenes last night, he told Sky News: "We live on the top floor. We could see the rioters coming closer. Aldi was on fire and barricades were being made by rioters. It was really scary."
Mr Radose, who went to stay at his father's house 10 minutes away, added: "We've gone back this morning and it's a complete shell. Everything we had is gone. It's just mad."
He went on: "So many people have lost everything. It's just crazy. It looks like its the the Second World War. It looks like the Blitz where we were living."
Mr Radose said he his wife had thought the situation was beginning to calm down at about midnight, but he then saw from his balcony that "things were getting worse and worse".
"There didn't seem to be a police presence at all. Buildings seemed to be allowed to burn. I guess they couldn't get there."
He added: "I think we've probably spent our last night Tottenham. We're just in shock."
Responding to last night's scenes of violence, a spokesman for 10 Downing Street said: "The rioting in Tottenham last night was utterly unacceptable.
"There is no justification for the aggression the police and the public faced, or for the damage to property.
"There is now a police investigation into the rioting and we should let that process happen."
Update:
A London Ambulance Service spokeswoman said paramedics had treated a total of 11 people, ten of whom were taken to hospital.
Two of the injured police officers needed attention from ambulance crews, but it is not yet clear whether the others were dealt with by the ambulance service.