The California Highway Patrol is identifying the driver as 52-year-old Quintin Watts of Stockton. Officers say they're investigating whether prescription or nonprescription drugs, or alcohol, were involved in Sunday's crash. They said it could be a combination.
Watts was arrested based on observations a witness made before the crash.
The bus did not have seat belts, the patrol said.
Officers are trying to determine the bus owner, but said based on a preliminary investigation, they're looking into a company called Cobbs Bus Service.