David Vargas, of Oakley, was arrested for homicide, assault with a firearm and shooting at a vehicle after investigators interviewed the suspect this morning, according to the Contra Costa County Sheriff's Office.
The shooting took place at 7 p.m. Saturday near O'Hara Avenue and Laurel Road, according to the sheriff's office.
Police responded to reports of shots fired and found Omar Martinez, 22, of Oakley, fatally wounded.
A second victim, a 16-year-old boy, is in stable condition at John Muir Medical Center in Walnut Creek.
Police believe two more victims might have been in the vehicle.
Investigators believe the suspected shooter knew his victims and was involved in an argument with them before the shooting.
Vargas' bail has been set at $1.8 million.
Anyone with information regarding the case is asked to contact investigators at (925) 313-2600 or (925) 646-2441.