Flores, 35, was in the northbound lanes of the highway near Concord Avenue about 9:20 p.m. when he lost control of his Chevrolet Silverado, according to the California Highway Patrol. The car went over an embankment and flipped onto its top, CHP officers said.
Flores was pronounced dead at the scene. An autopsy was completed this morning and toxicology reports are pending, said Contra Costa County sheriff's Sgt. Bryan Reynolds.
An adult male passenger was hurt in the crash, and was taken to John Muir Medical Center in Walnut Creek, Reynolds said.