Oakland's mayor and police chief acknowledged Saturday falling short in controlling what police said was a night of some of the heaviest damage yet in peaceful marches that have turned violent.

Up to 400 people roamed dozens of blocks of Oakland's downtown Friday night to Saturday morning, breaking the glass fronts of banks and a few other businesses and systematically smashing the windshields of rows of vehicles at one car lot.

Police Chief Sean Vincent, speaking Saturday to reporters at City Hall, said the overnight damage "was amongst the worst we had seen" in more than 1½ years of sometimes-violent protests here over instances of police killings of African-American men around the country.

After a long day Friday of May Day marches by labor supporters and by protesters against police violence nationally, Oakland police had trouble dealing with a nighttime crowd that turned "larger than we expected and angrier than we expected," Vincent said.

The rampage came on the same day that prosecutors in Baltimore, Maryland, charged six officers in a high-profile death of an African-American man. While that news brought people out on the streets to celebrate in Baltimore, it also contributed to new and occasionally violent protests in some cities.

At a downtown Oakland car lot on Saturday, security-company owner Steve Tittle walked through what had been a plate-glass door of a business storing new Hyundais and Hondas for car dealers. "Step into my office," Tittle joked, while avoiding the broken window glass that now surrounded the smashed and empty door frame.

Protesters had smashed the front and back windows of dozens of new cars in the lot, and set alight a Hyundai Elantra.

"This is not civil disobedience," Tittle said. "This is an anarchy, chance-to-destroy mob, nothing else."

Asked what he thought would stop the vandalism to businesses, Tittle said, "Punishment."

The auto lot marked the heaviest damage in downtown Oakland, a center of political activism in the San Francisco Bay Area as well as home to some of its poorest neighborhoods.

Police said they arrested a dozen people on charges that included burglary, failing to disperse and vandalism.

The only injury reported was a cut leg suffered by one officer. Police used force only twice — once when officers fired a tear-gas canister and once when an officer tackled a violent protester, Vincent said.

Mayor Libby Schaaf, who stayed on the streets overnight monitoring the crowds and talking to owners of damaged businesses, said city officials "did not do as good a job as we should have protecting property."

She gave no details of what she wanted to see done differently to protect property.

Not every Oakland resident wanted to see a crackdown, however.

Community organizer Ruby Reid, who lives within earshot of the sound of breaking windows and police loudspeakers overnight, said the violence of the protests was overstated and the messages against heavy-handed policing important.

"Actual violence is people getting hurt, people getting shot" in police custody, she said.