Riot police fought running skirmishes with anti-Wall Street protesters on Saturday, firing tear gas and bean bag projectiles and arresting more than 200 people in clashes that injured three officers and at least one demonstrator.
Three police officers and one protester were injured during the clashes, the city said, without detailing their conditions. Internet broadcasts by activists showed several demonstrators being treated by paramedics or loaded into ambulances.
The scuffles erupted in the afternoon as activists from the Occupy movement sought to take over a shuttered downtown convention center, sparking cat-and-mouse battles that lasted well into the night in a city that has seen tensions between police and protesters boil over repeatedly.
"Occupy Oakland has got to stop using Oakland as its playground," Mayor Jean Quan, who has come under criticism for the city's handling of the Occupy movement, said at a late evening press conference.
"Once again, a violent splinter group of the Occupy movement is engaging in violent actions against Oakland," she said, speaking as officers in riot gear were still lined up against demonstrators in downtown intersections.
City Council President Larry Reid said a group of protesters broke into City Hall, damaging exhibits and burning a U.S. flag.
Occupy Oakland organizers had earlier vowed to take over the apparently empty downtown convention center to establish a headquarters, hoping to revitalize a movement against economic inequality that lost momentum after police cleared protest camps from cities across the country late last year.
They also hoped to draw attention to homelessness in the attempted building takeover, seen as a challenge to authorities who have blocked similar efforts before.
A police spokesman said more than 200 people had been arrested during the day following altercations that began when activists tried to tear down a chain-link fence surrounding the Henry J. Kaiser Convention Center.
"The 1 percent have all these empty buildings, and meanwhile there are all these homeless people," protester Omar Yassin said.
'IMPROVISED EXPLOSIVE DEVICES'
Police in riot gear moved in, firing smoke grenades, tear gas and bean-bag projectiles to drive the crowd back.
"Officers were pelted with bottles, metal pipe, rocks, spray cans, improvised explosive devices and burning flares," the Oakland Police Department said in a statement. "Oakland Police Department deployed smoke and tear gas."
Some activists, carrying shields made of plastic garbage cans and corrugated metal, tried to circumvent the police line, and surged toward police on another side of the building as more smoke canisters were fired.
"The city of Oakland welcomes peaceful forms of assembly and freedom of speech but acts of violence, property destruction and overnight lodging will not be tolerated," police said in a statement.
Hundreds of demonstrators regrouped and marched through downtown Oakland, where they were repeatedly confronted by police in riot gear. Police at several points fired flash-bang grenades into the crowd and swung batons at protesters.
A group of demonstrators ultimately made their way to City Hall, where they brought out a U.S. flag and set it on fire before scattering ahead of advancing officers.
Several hundred people remained in the streets well after dark, facing off against lines of riot police holding batons who demonstrators sometimes taunted as "pigs."
Protesters in Oakland loosely affiliated with the Occupy Wall Street movement that began in New York last year have repeatedly clashed with police during a series of marches and demonstrations.
Elsewhere, the National Park Service said on Friday it would bar Occupy protesters in the nation's capital, one of the few big cities where Occupy encampments survive, from camping in two parks where they have been living since October.
That order, which takes effect on Monday, was seen as a blow to one of the highest-profile chapters of the movement.
(Writing by Dan Whitcomb and Mary Slosson; Editing by Cynthia Johnston and Bill Trott)