Angry crowds clash with police in Berkeley, Calif.

BERKELEY, Calif. - Protests in New York and Missouri have died down, but angry crowds in one California city famous for activism spent much of the weekend blocking traffic and clashing with police in this ultra-liberal bastion thousands of miles from where Michael Brown and Eric Garner were killed.

Although many activists in other parts of the country have gone home, protests in Berkeley and Oakland are still active, reflecting the area's long history of protest dating back to the 1960s.

The crowds that came out to protest in Berkeley numbered only a few hundred, but some are not college students or residents so much as full-time demonstrators who protest anything - war, prison conditions, and economic inequality - and sometimes use demonstrations as a pretext for violence and vandalism, just as they did during the Occupy Wall Street movement.

Berkeley Mayor Tom Bates said a tiny fraction of protesters are obscuring the wider message calling for reform of policing policies nationwide.

"The people in the Bay Area are sensitive to worldwide issues," Bates said. "Unfortunately, there is a small element that uses violence at times to make their point."

Merchants on Monday cleaned up broken glass and took stock of the previous night's looting from downtown stores.

Bates called the violent elements of the demonstration "cowards and thugs who need to take off their masks."

It was not immediately known how many businesses were damaged, and no damage estimate was offered. Five people were arrested, police said.

Stuart Geiger, 27, a UC Berkeley doctoral student, attended the protest and recorded video of peaceful demonstrators attempting to stop the looting of a Radio Shack.

"There was a pretty vocal sentiment there about keep this a peaceful protest and stay on message," Geiger said.

A peaceful protester was struck by a hammer and slightly injured when he tried to stop looting.