A line of police officers in riot gear blocked the ramp to the freeway.
Some protesters managed to get around officers and onto the freeway but were forced back. Then protesters retook the highway, halting traffic in both directions.
Dozens of protesters also marched to the railroad tracks, blocking an Amtrak train. A protester held up a sign "Black lives matter" in front of the stopped train.
Leman Woods, 41, came to the protests after getting off work at UC Berkeley.
"I'm here because I am tired of police brutality," Woods, an Oakland resident, said.
He said it has been painful to watch news coverage of the police shooting of unarmed teenager Michael Brown and the chokehold death of Eric Garner.
"It's sad, it's hard," Woods said. "It shouldn't be happening to nobody of any race or color. And police just get away with it."
Peaceful protesters confronted protesters vandalizing and looting businesses and cleaned up trash they left in the streets.
Bates said protesters causing damage are undercutting the point of the demonstrations.
"It's really striking out at the wrong thing and diminishing from the message which is we need to do something about police and community relations," Bates said.
The demonstrations were just the latest to express growing frustration across the country with grand jury decisions in Missouri and New York not to indict white police officers in the deaths of two African-American men.
Bates said police would continue to try to keep the demonstration "as peaceful as possible and protect the public's lives and safety."
Source: USA Today; Contributing: William M. Welch in Los Angeles; Associated Press