The shooting was reported around 11 a.m. in the 800 block of 52nd Street, about a block and a half from the hospital, spokeswoman Johnna Watson said.
Two victims, both males, were struck by the gunfire. One succumbed to his injuries while the other is at a hospital with life-threatening injuries, Watson said.
A third person was injured but the wound was not from a gunshot, and it was unclear whether the injury occurred at the scene or elsewhere, according to Watson.
Children's Hospital was shut down as a precaution for about 15 minutes following the shooting, according to Rebecca Casais, a nurse who works at the hospital.
No one is in custody for the shooting and no suspect information was immediately available, Watson said.
Anyone with information about the case is encouraged to call the Oakland Police Department's homicide section at (510) 238-3821 or email firstname.lastname@example.org.