Forty-five officers from several law enforcement agencies responded, including Berkeley police, Oakland police and the California Highway Patrol, officials said. At least two people -- current and former students -- were arrested.
Students had attended an event called the Rolling University, a series of teach-ins on state and UC budgets and other education issues, followed by a dance at Sproul Plaza, just off Telegraph Avenue, UC police Capt. Margo Bennett said.
The party and protest had been uneventful until about 11 p.m., when the first call came to campus police reporting problems.
When officers arrived, they found someone had cut a chain on the fence surrounding Durant Hall, a former library in the center of campus that is closed for renovations, and hung a banner reading "March 4" above the entrance to the building, a reference to a statewide "Day of Action" planned for next week to protest education budget cuts, university spokeswoman Janet Gilmore said.
At least 10 people were found inside the building. Several windows had been broken, graffiti was sprayed on interior walls, portable toilets turned over and construction equipment thrown around.
The university could not immediately estimate the cost of the damage.
"They basically trashed it," Gilmore said.
As of Friday afternoon, the administration had no idea what the group was protesting, she said.
Crowds outside the building continued to swell, and by about 1:30 a.m., people began to clash with police, throwing bottles, setting trash ablaze and breaking several windows on Telegraph, including the plate-glass front windows of a Subway sandwich shop, police said. Protesters lit a large garbage container on fire, then rolled it into the street.
A video of the protest from ABC7 News shows police in riot gear clashing with protesters, hitting some of them with batons. Two Berkeley police officers received minor injuries from thrown objects, which included a fire extinguisher, fire hydrant cap, rocks and bottles, Berkeley police spokesman Andrew Frankel said.
Arrested were Marika Goodrich, 28, and Zachary Miller, 26, both of Berkeley, Frankel said. According to a UC news release, Goodrich, a UC Berkeley student, was charged with obstructing a peace officer, inciting a riot and assaulting a peace officer and is being held on $32,500 bail. Miller, who was a UC Berkeley student last semester but is not registered this semester, faces three charges, including inciting a riot and obstructing an officer. He is being held on $22,500 bail.
A protest leader, UC Berkeley student Callie Maidhof, defended the vandalism and said rioters targeted the sandwich shop because a second Subway is scheduled to open on campus, just across Bancroft Way.
"There will be two Subways within 100 feet of each other," she said.
The crowd finally dispersed just before 4 a.m., police said. Much of the damage along Telegraph Avenue had been cleaned up by the time businesses opened Friday morning.
Roland Peterson, executive director of the Telegraph Avenue Business Improvement District, said he walked the district early in the morning and the only damage to businesses was the broken window at Subway at Durant and Telegraph avenues.
"We certainly hope this won't happen again on March 4," Gilmore said. "We hope that will be a peaceful event."
The rioting followed a December protest that left the UC Berkeley chancellor's campus home damaged. A mix of students and nonstudents have been involved in recent protests, and the demonstrations have involved issues ranging from student-fee hikes to campus construction.
Tensions first escalated in November, when protesters blocked access to Wheeler Hall, a large classroom building, shortly after UC regents voted to raise student fees by 32 percent. Demonstrators said UC police beat them at that protest, leading to an apology by Chancellor Robert Birgeneau.