Officers responded just after 9 a.m. to the 1600 block of 83rd Avenue after activation of the city's ShotSpotter gunfire detection system, police said.
Several people were involved in a "verbal altercation" when someone fired multiple times at a group, striking the victims, police said. The shooter fled in a vehicle.
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Two of the victims were pronounced dead at the scene and two were taken to area hospitals, where they were listed in critical condition, police said.
The names of the dead were withheld pending notification of their next of kin, police said.
Anyone with information is asked to contact the Oakland Police Department's Homicide Section at (510) 238-3821 or Tip Line at (415) 238-7950.