Kevin Stone, 29, of Clearlake, was found at 1:20 a.m. on Aston Way in a Ford Explorer that was stolen in Lake County, sheriff's Sgt. Carlos Basurto said.
Stone is suspected of fatally shooting 4-year-old Skyler Rapp and wounding five others at a backyard barbecue in Clearlake on June 18. Two other Lake County men have been arrested in connection with the shooting.
Stone's girlfriend Leighann Painchaud, 25, also was in the Explorer and was arrested on suspicion of vehicle theft, Basurto said.
The sheriff's office learned around 10:30 p.m. Thursday that Stone was seen driving the Explorer in several different areas of Santa Rosa.
Deputies and detectives searched several areas and got a tip around 1:20 a.m. that Stone was parked on Aston Way in the South Park neighborhood, Basurto said.
Stone and Painchaud were arrested without incident.