The crowd was mostly peaceful, the Oakland Tribune reported. Community leaders, including Mayor Ron Dellums, appealed for calm.
The killing of Oscar Grant III on Jan. 1, 2009, by Johannes Mehserle, a police officer with Bay Area Rapid Transit, outraged many in Oakland. Grant, who was unarmed, was shot in the back.
Streets were closed because of the number of people who gathered Thursday, and buses had to be rerouted. At one point, a group of people surrounded a bus and refused to let it move.
Oscar Grant Sr., the young man's 64-year-old grandfather, addressed protesters Thursday.
"Don't come out here to fight," he said. "Don't dishonor my grandson's death by coming out here and tearing up Oakland. ... I know the verdict was wrong, but let's not tear up Oakland for it."
Many in the crowd echoed his sentiments. Brenda Appleby talked to a man urging protesters to riot.
"Maybe the verdict is wrong, but this is my community and my town," she said.