Bearing a banner declaring “Black and Breathing,” protesters surrounded and temporarily blockaded the Oakland Police Department headquarters on Monday morning while shutting down a nearby freeway entrance to demand “an immediate end to the war on Black people.”

“We fight for justice for every single Black life that has passed at the hands of police, but we must also stand up and shut down for the Black and breathing who are at risk of the same fate,” said Deirdre Smith, one of the coordinators of the action, which was organized under the leadership of all-black organizations the BlackOut Collective, #BlackBrunch and #BlackLivesMatter.

Chaining themselves together, demonstrators blocked four sets of doors to the Oakland Police Department while approximately 30 black protesters held the space in front of the station. Meanwhile, others shut down a major intersection leading to a freeway close by, causing significant traffic disruption.

At one point, a demonstrator scaled a pole to replace an OPD flag with one memorializing Oscar Grant, Eric Garner, Alex Nieto, Renisha McBride, and Michael Brown—all people of color, almost all of them black, killed by police or vigilante violence. A group of people locked together at the base of the pole to prevent the alternate flag from being taken down.

At the time of publication, organizers announced that they had reached their goal of maintaining the blockade for 4 hours and 28 minutes. “The 4 hours honor the memory of Michael Brown, whose body lay in the streets of Ferguson for more than 4 hours after he was killed by a police officer,” explains a joint statement. “The 28 minutes highlight the startling fact that every 28 hours a Black person is killed by police, security or vigilantes in this country.”

Protesters say that now is the moment to take a stand against this deadly status quo.

“This action is part of a larger, sustained effort to disrupt business as usual in the tradition of the Montgomery Bus Boycott and the Woolworth counter sit-ins,” said Jeralynn Blueford, the mother of Alan Blueford who was killed by an Oakland police officer in 2012.

“We didn’t get an equal seat on the bus or at the lunch counter because we said ‘please,'” Blueford continued. “We got our seats because of our highly organized and effectively sustained protests and boycotts, disrupting business as usual. We hold this space today as a demonstration of Black peoples’ right to exist and to thrive, just like anyone else.”