The crash occurred just after 11 a.m. on eastbound Highway 24 near the Pleasant Hill Road exit in Lafayette.
Witnesses told the CHP that the driver of the vehicle involved was speeding before the car went off of the roadway and struck a tree, a CHP officer said. The driver, who was alone in the car, died at the scene.
Emergency responders searched for additional victims but found none, according to Capt. Robert Marshall of the Contra Costa County Fire Protection District.
The far right lane of the highway remained blocked by emergency vehicles as of 12:30 p.m.
Officials tell ABC7 News that the victim is a 17-year-old from Danville.