Occupy Oakland demonstrators
© Reuters / Stephen Lam
Occupy Oakland demonstrators confront a line of police officers during a demonstration in attempt to occupy a vacant building near Laney College in Oakland, California January 28, 2012
Police in Oakland, California, have used tear-gas and flash-grenades as a 2,000-strong Occupy Oakland march turned violent, with some protesters claiming that rubber bullets were also fired into the crowd. At least 300 people were arrested.

The demonstrators had attempted to take over vacant buildings to use as their headquarters, they also broke into City Hall and tried to occupy a YMCA. Police spokesman Jeff Thomason told media most of the arrests came around 8 pm local time. Police took many protesters into custody as they marched through the city's downtown area, with some entering a YMCA building.

Officials say, at one point protesters began tearing down perimeter fences around the Henry J. Kaiser Convention Center, as some attacked police officers, throwing rocks, bottles and other objects. Police declared an unlawful assembly and used force, according to the Oakland Tribune newspaper.

While police were taking people into custody near the YMCA, about 100 officers surrounded City Hall, while others swept the inside of the building for protesters who had broken in. Inside the building, protesters burned flags, broke into an electrical box and damaged several art structures, according to Oakland Mayor Jean Quan.

"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," the press release by city officials stated. "The Oakland Police Department is also committed to facilitating peaceful forms of expression while protecting personal safety and property through ethical and constitutional policing."

At the moment, the Occupy crowd in the city's central square is being monitored by dozens of police officers.

Oakland has seen one of America's largest and most vocal Occupy protests, with thousands of people attending since the demos started in October. Some 300 people have been arrested since then. The Occupy Wall Street movement started in September in New York and claims to represent the 99 per cent of Americans, who suffer from corporate greed and economic injustice.

Oakland demonstrators shield themselves
© Reuters / Stephen Lam
Occupy Oakland demonstrators shield themselves during a confrontation with the police near the Oakland Museum of California in Oakland, California January 28, 2012

Members of the Oakland Police
© Reuters/Stephen Lam
Members of the Oakland Police Department arrest an Occupy Oakland demonstrator during a confrontation in Downtown Oakland, California January 28, 2012