A San Ramon man died in a two-car crash Monday on Interstate Highway 680 in Walnut Creek, according to the California Highway Patrol.
The collision involving a black 1974 Porsche and a black Jeep SUV was reported shortly before noon on northbound I-680, just north of the North Main Street off-ramp.
The Porsche's driver, a 63-year-old San Ramon resident, was unresponsive and taken to John Muir Hospital in Walnut Creek, where he died from his injuries, the CHP said.
His name has not been released.
Two people in the Jeep sustained minor injuries and were not hospitalized.
The cause of the collision is still under investigation.
An alert for heavy traffic was issued after the crash and three lanes were closed. The lanes reopened about 2 p.m.
Alcohol or drugs were not involved in this collision. Anyone with information regarding the crash or the events leading up to it is asked to contact Contra Costa CHP at (925) 646-4980.