LONDON — A chaotic wave of violence and looting raged across London and spread to three other major British cities, as authorities struggled to contain the country’s worst unrest since race riots set the capital ablaze in the 1980s.

By Tuesday, police called in hundreds of reinforcements – and made a rare decision to deploy armored vehicles in some of the worst-hit districts — but still struggled to keep pace with the chaos unfolding at flashpoints across London, in the central city of Birmingham, the western city of Bristol and the northwestern city of Liverpool.

The riots appeared to have little unifying cause, though some involved in the violence claimed to oppose sharp government spending cuts which will savage welfare payments and see tens of thousands of public sector jobs lost through 2015.

Others appeared attracted simply by the opportunity for violence. “Come join the fun,” shouted one youth, racing along a street in the east London suburb of Hackney, where shops were attacked and cars torched.

The fatal shooting of a black man by police a week earlier was also being cited as a cause for the unrest.

Violence first broke out late Saturday in the low-income, multiethnic district of Tottenham in north London, where outraged protesters demonstrated against the fatal police shooting of Mark Duggan, a 29-year-old father of four, who was gunned down in disputed circumstances Thursday.

Duggan’s death stirred old animosities and racial tensions — similar to those that prompted massive riots in the 1980s — despite efforts by London police to build better relations with the city’s ethnic communities after high-profile cases of racism in recent decades.

A brief inquest hearing into Duggan’s death was set to take place Wednesday though it will likely be several months before a full hearing is convened.

Police said Duggan was shot dead when police 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 and media reports said a bullet had been found in an officer’s radio. However, the Guardian newspaper reported that the bullet in the radio was police-issued, indicating Duggan may not have fired at the officer.

Duggan’s partner, Semone Wilson, insisted that her fiance was not connected to gang violence and called on police to offer more information about his death. She rejected suggestions that the escalating riots were linked to protests over his death. “It got out of hand. It’s not connected to this anymore. This is out of control,” she said.

That was the view also of 37-year-old Marcia Simmons, who has lived in Tottenham, an ethnically diverse neighborhood, all her life. “It’s nothing to do with the man who was shot, is it?” she said. “A lot of youths … heard there was a protest and joined in. Others used it as an opportunity to kit themselves out, didn’t they, with shoes and T-shirts and everything.”

As the unrest spread, some pointed to rising social tensions in Britain as the government slashes 80 billion pounds ($130 billion) from public spending by 2015 to reduce a huge budget deficit, swollen after the country spent billions bailing out its foundering banks.

“This is the uprising of the working class. We’re redistributing the wealth,” said Bryn Phillips, a 28-year-old self-described anarchist, as young people emerged from a store in Hackney with chocolate bars and ice cream cones.

Phillips claimed rioters were motivated by distrust of the police and he drew a link between the rage on London’s street and insurgent right-wing politics in the United States. “In America you have the tea party, in England you’ve got this,” he said.

Matthew Yeoland, a 43-year-old teacher watching the unrest in Peckham, said, tension had existed for a long time. “The kids aren’t happy. They hate the police. It’s like a war zone and the police weren’t doing anything. There were too many people and not enough police.”

But, as he watched the violence unfold, Alan McCabe, a resident in Croydon, said, “I have never seen such a disregard for human life. I hope they rot in hell. The grief they have caused people, the fear they have put in people’s hearts, decent people who have done nothing to anyone,”

Police were also taking a tough stand against the rioters.

“The violence we have seen is simply inexcusable. Ordinary people have had their lives turned upside down by this mindless thuggery,” Police Commander Christine Jones said.

This report was compiled from a dispatch by The Associated Press.