Administrators told students they could protest around the clock for a week, if they didn't pitch tents. The protesters decided not to comply and set up a tent site they dubbed "Occupy Cal."
The student newspaper says then members of Occupy Oakland jointed the protest.
TV news footage Wednesday night showed police officers pulling people off the steps of the university's main administration building and nudging others with batons, as the crowd chanted "We are the 99 percent!" and "Stop Beating Students!"
Earlier in the day campus police and Alameda County sheriff's deputies dismantled a small encampment students had set up at another site on campus.
The University says six students and one faculty member were arrested.