A small group of demonstrators tried unsuccessfully to shut down Oakland's federal courthouse Wednesday following four nights of large, often violent protests in Berkeley against the killings of black men by white police officers.

About 50 nonviolent protesters blocked the courthouse's front and back entrances, but employees entered through side doors.

The protest involved white community members who joined religious leaders under the message "white silence equals violence, black lives matter."

Protesters have rallied for weeks following grand jury decisions not to indict a Ferguson, Missouri, officer in the killing of Michael Brown and a New York City officer who was seen on video applying a fatal chokehold on Eric Garner.

The protest was quiet compared to activity a night earlier.

Authorities arrested at least 19 people in the East Bay area Tuesday night. Berkeley police arrested five adults and one juvenile, and the California Highway Patrol apprehended 13 others.

Protesters briefly blocked traffic on state Route 24, which connects Berkeley to Oakland, and some hurled rocks, projectiles and incendiary devices at CHP officers, a spokesman said.

A police spokesman in nearby Emeryville said some protesters threw bottles and chunks of concrete at officers and damaged some stores.