A Danville man died after veering off Interstate 680 and crashing his truck into an unoccupied house in Pleasant Hill on Tuesday morning, according to the California Highway Patrol.
The Contra Costa County coroner's office later identified the man killed as 77-year-old Wallace Ryburn.
CHP officials said it wasn't immediately clear if Ryburn experienced a medical emergency while driving on the freeway, precipitating the crash.
The incident took place just before 9 a.m. Tuesday, when a white Ford F-250 traveling southbound on I-680 abruptly veered to the right and hit two other cars just south of the Monument Boulevard exit, CHP officials said. The drivers of the other two vehicles were uninjured.
The Ford truck continued veering right, went off the roadway and drove through a cyclone fence before traveling across Contra Costa Boulevard and crashing into an empty house, according to the CHP.
Ryburn was unconscious and unresponsive in the truck when emergency personnel arrived and began administering life-saving procedures, according to the CHP. The Danville man was quickly taken to John Muir Medical Center in Walnut Creek, where he was pronounced dead, officials said.
"At this time it is unclear if the driver died from his injuries from the collision or a medical condition," CHP officials said, adding that drugs or alcohol do not appear to have been factors in the crash.
The incident remains under investigation. Anyone with information on the crash can contact the CHP Contra Costa Area Office at 646-4980.
Editor's note: Information from the Bay City News Service was used in this report.