The shooting occurred at about 2 a.m. near the intersection of Second and Brush streets, Alameda police Lt. Bill Scott said.
Responding officers found the victim conscious and communicative, and he was transferred to Highland Hospital for treatment, according to Scott.
Scott said the suspect left the scene in an unknown vehicle, and no arrests had been made as of this afternoon.
The victim appears to have known the suspect.
Police were still trying to determine a motive this afternoon, Scott said.