LAFAYETTE--A 17-year-old Danville boy was killed Thursday morning after allowing his car to drift and smashing into an embankment on eastbound Highway 24, according to the California Highway Patrol.

The victim, whose identity has not been released, was reportedly driving at more than 100 mph when he lost control of his Isuzu Impresa near Pleasant Hill Road just after 11 a.m. The car hit a traffic sign and continued down an embankment before coming to a stop, according to Lt. Steve Perea, of the California Highway Patrol. No other vehicles were involved.

The driver, who was alone in the car, died at the scene.

David Wilson, of San Ramon, was driving in the area and saw the Isuzu zoom by, weaving in an out of lanes.

"The boy was racing another a white Mustang convertible," Wilson said.

The information could not be immediately confirmed by the California Highway Patrol.

Contact Karina Ioffee at 650-576-9626. Follow her at Twitter.com/kioffee.