Concord police Sgt. Carl Cruz said the man appeared in the emergency room of the Concord campus of John Muir Medical Center at about 7:30 p.m.
He was conscious and police were able to speak with him in the emergency room, but he was "very uncooperative," according to Cruz, and refused to tell police what had happened to him or how he got to the hospital.
The investigation into the incident is ongoing, he said.
Anyone with information about the shooting is asked to call the Concord Police Department at (925) 671-3241.