The shooting was reported at 11:02 a.m. at an apartment complex in the 27000 block of Sleepy Hollow Avenue, Hayward police Sgt. Mark Ormsby said.
The victim was transported to an area hospital with life-threatening injuries and is in surgery this morning, Ormsby said.
Police remain at the scene of the shooting and are continuing to investigate the incident.
No suspect information has been released, Ormsby said.