Dozens of police maintained a guard around City Hall in Oakland, California, yesterday following weekend clashes with protesters that resulted in 300 arrests.
Earlier, Occupy Oakland demonstrators broke into the historic building and set fire to a US flag.
The protests – the most turbulent since Oakland police forcefully dismantled an Occupy encampment in November – came days after the group said it planned to use a vacant building as a social centre and political hub and threatened to try to shut down the port, occupy the airport and take over City Hall.
Protesters clashed with police throughout Saturday, at times throwing rocks, bottles and other objects at officers. Police responded by deploying smoke, tear gas and bean bag rounds, city administrator Deanna Santana said.
The number of demonstrators swelled as the day wore on, with afternoon estimates ranging from about 1,000 to 2,000.