The crash happened just before 11:15 p.m. near 85th Avenue and International Boulevard, the Oakland Fire Department said.
Three people were pronounced dead at the scene. Three others were taken to local hospitals, including two in critical condition and one in serious condition.
Two more people were awaiting medical transport with minor injuries, including a person the fire officials described as the suspect.
Authorities urged people to avoid the area.
The Oakland Police Department did not immediately provide additional details, including the identities of those killed, the ages of the victims, or what led up to the crash.
Oakland’s traffic fatality dashboard showed six traffic deaths from January through April, including three pedestrians, before any update from Saturday night’s crash.
The crash follows another recent mass-injury pedestrian collision in Oakland. On May 2, seven people were injured after a driver struck pedestrians in the city’s uptown neighborhood, according to police.