At one point, rioters broke through police ranks and attempted to storm Tottenham's police station, pelting officers with bricks, bottles and eggs. As a police helicopter flew over Tottenham High Road, youths in masks and hoods added combustible material to two burned out police cars, included a bundle of documents and an awning ripped down from one of the shops. Some attempted to persuade the rioters to disperse, one young man shouting: "Go home now people.”

But others filled bottles with petrol to throw at the police lines. Many lined up with makeshift weapons including metal bars and baseball bats to confront the line of police, but others seemed more interested in looting. At one stage a safe was dragged out of a book-makers, while others were seen with a television set and an electric guitar. Several arrived with shopping trolleys to take away what they had stolen.

"It wasn't like this before," said one woman standing close to one of the two burned-out police cars. "It started out as a peaceful demonstration. The police shot a guy here last week and they lied about what happened. They said he pulled a gun but he wouldn't have done that with armed police. They shot him so badly that his mother could not recognise him.”

A Metropolitan police spokesman said the trouble began when missiles were thrown at parked patrol cars at 8.30pm. He said one was pushed, blazing, into the middle of Tottenham High Road. Neither of the two officers who had been driving the cars was injured.

As violence spread, a double-decker bus was set upon. Witnesses said the vehicle exploded in flames after attackers threw homemade bombs through its windows. Nearby shops were also set ablaze.

Most of the crowd consisted of onlookers, who jeered at police vans as they arrived. There were chants of "we want answers" and "whose streets? Our streets.”

Officers from the Territorial Support Group charged at rioters and attempted to block off side streets. Riot police, some with dogs, shepherded people away.

Police on horseback also attended the scene, along with reinforcements from the City of London police. A police helicopter hovered above.

Hails of bottles and bricks were intermittently thrown at police from side streets as reinforcements arrived. Rioters also aimed fireworks at police. At one stage, four firework rockets were shot at a line of horses, prompting a charge and a nearby crowd to disperse in panic.

Hundreds of residents gathered to watch the unrest and there several were reports of attacks on bystanders. At one point rioters were seen beating up a man attempting to take film footage of the scene.

Local resident David Akinsanya, 46, said several shop windows had been smashed. "It's really bad," he said. "There are two police cars on fire. I'm feeling unsafe. It looks like it's going to get very tasty. I saw a guy getting attacked." Maria Robinson, another resident, told the BBC: "The police seem very frightened at the moment, people are unstoppable. They've broken into various businesses, jewellery shops, bookies, it's absolutely crazy. They’ve beaten up a man for talking to the fire brigade.”

Attempts by police to gain some control succeeded by 11.30pm, as they cleared an area of the street with the worst fires, allowing two fire engines onto the street.

Twitter was abuzz on Saturday night with messages of support and condemnation.

A police source said acting Met police commissioner, Tim Godwin, was being kept informed of events.

Met police commander Stephen Watson said the situation was "complex and dynamic". He told Sky News the setting up of the Gold command structure earlier in the evening - a response to major public order events - was a routine contingency plan.

Although the police were aware of increased tensions in the area since the death of Duggan, Watson said they had no warning that a riot would break out.

Police were unable to confirm whether the violence was connected to outrage over the death of Duggan, 29, who was shot in a police anti-firearms operation in Tottenham.

The violence broke out at dusk after about 120 people marched on Tottenham police station to express anger over the death of Duggan. The protesters had begun their march in the Broadwater Farm area, the scene of riots in 1985 in which a police constable, Keith Blakelock, was killed by attackers wielding knives and machetes.

A family friend of Duggan, who gave her name as Nikki, said that the dead man's friends and relatives had organised the protest to demand “justice for the family.”

"They're making their presence known because people are not happy,” she said. "This guy was not violent. Yes, he was involved in things, but he was not an aggressive person.”

It was revealed on Saturday that Duggan had been shot in an exchange of fire after the police's Trident unit, which deals with gun crime, stopped the vehicle he was travelling in. A police officer was said to have escaped injury in the shootout when a bullet lodged in his radio.

Mayor Boris Johnson said where there were real concerns in the community it was right there was a proper investigation and that the IPCC was looking into Duggan's death. "The violence to property will do nothing to facilitate that investigation," the mayor said.

David Lammy, the local MP, called for calm on Saturday night, saying the community was anxious. The Independent Police Complaints Commission rushed out a statement in an attempt to appease the anger saying it is in close contact with the Duggan family and will have further meetings with them on Sunday.