The sheriff's office began receiving 911 calls at about 9:30 p.m. Wednesday from people reporting gunshots, spokesman Jimmy Lee said.
Deputies responded and found the victim, identified as Jerry Owens, in the 1600 block of Third Street. He was pronounced dead at the scene, Lee said.
A second shooting victim, a 26-year-old man, was found inside a residence. He was transported to John Muir Medical Center in Walnut Creek, where he was in stable condition today.
As of Thursday morning, investigators had not identified any suspects and had not determined whether the incident was connected to another shooting Tuesday night about a block away in the area of Third Street and Grove Avenue.
Deputies were alerted to that shooting at about 11 p.m. when the Richmond Police Department's ShotSpotter system detected gunfire in the area.
When deputies arrived, they didn't find any victims, but about 15 minutes later they learned a gunshot victim had arrived at Doctors Medical Center in San Pablo.
The victim, identified as 21-year-old North Richmond resident Ervin Coley III, was airlifted to John Muir Medical Center, where he died.
Anyone with information about either case is asked to call the sheriff's office investigations division at (925) 313-2600.