Protesters blocked traffic on the Bay Bridge heading into San Francisco, on Martin Luther King Jr. Day.

Videos posted on social media show activists sporting Black Lives Matter shirts and signs, chaining themselves and several cars along the width of the westbound bridge pass. Many can be seen yelling for the resignation of local officials, including Oakland Mayor Libby Schaaf, Oakland Police Chief Sean Whent and San Francisco Police Chief Greg Suhr.

Westbound traffic was brought to a standstill for up to 45 minutes, according to local reports.

In a press release, Black.Seed, a Black, gay rights group, took credit for the protests, calling for a stop to "anti-Back racism and terrorism" and "police murders" in the Bay Area. The group says the area saw dozens of deaths at the hands of police in 2015, including eight black men in Oakland alone.

"For the second year in a row, the Anti Police Terror-Project (APTP) put out a call for 96 Hours of Direct Action to reclaim Dr. Martin Luther King Jr's radical legacy and take a stand against anti-Black racism and terrorism. In a courageous display of solidarity and the spirit of MLK, Black.Seed, a Black, queer liberation collective, has shut down the Bay Bridge as a show of resistance to a system that continues to oppress Black, Queer, Brown, Indigenous and other marginalized people throughout the Bay Area."

Twenty-five protesters were arrested, according to California Highway patrol.

All lanes were reopened after about 90 minutes after the protesters began to shutdown the bridge.

Elsewhere on Monday, protesters interrupted an MLK Day speech by San Francisco Mayor Ed Lee, calling for an investigation and resignation of the city's police chief and several of his officers for a police shooting in December that left a 26-year-old black man dead.