Organizers called for the gathering to meet outside Oakland's Fruitvale BART station at 3 p.m. and they started marching around 4 p.m.
The marchers called for justice for Mike Brown, the teenager shot and killed in Ferguson, Missouri, and Eric Garner, killed in a police chokehold in New York. Both deaths occurred last year, according to organizers.
A group of about 50, slimmed down from about 100 people at the beginning of the march, made it to the police substation at 2651 73rd Ave. around 6 p.m., according to police.
The protest ended around 7 p.m.
Police spokeswoman Officer Johnna Watson said in an email tonight that the march was "largely peaceful." There were four arrests for "various crimes," which were not specified.
The march was a part of a series of protests and rallies held this holiday weekend throughout the Bay Area and beyond in honor of the birthday of civil rights leader Dr. Martin Luther King Jr. King was assassinated in 1968. It is the first of three to be held in Oakland over the Martin Luther King holiday weekend.
There were protests on BART Friday morning as well. Demonstrators banged metal spoons on subway pillars and blocked passengers from getting off trains during the morning commute in San Francisco.
VIDEO: BART ridership down Friday due to protest
There are plans to make this a weekly event that will be held on Fridays.
VIDEO: Protesters plan weekly protests
BART has long-term plans in place if protests are held on a weekly basis.
Four years ago, the hacker group Anonymous held weekly protests every Monday on BART.
For full coverage on the protests against police brutality, click here.
Bay City News contributed to this report.