SAN RAMON (CBS SF) — Two people were killed, and two others injured in a fiery crash on Interstate Highway 680 in San Ramon early Sunday morning, the California Highway Patrol said.

CHP investigators said a Volkswagen Jetta was southbound on I-680, north of Alcosta Boulevard, around 3:30 a.m. when it went off the roadway to the right and then swerved back and hit the center median.

The Jetta stopped sideways, blocking the left lane.

It was then struck by a Ford Fiesta, causing major damage to both cars and starting a fire that engulfed the Jetta, killing two people trapped inside.

“When officers were responding, one vehicle was on fire,” said CHP Sgt. Andrew Murphy.

A third person in the Jetta suffered major injuries and the driver of the Fiesta had moderate injuries. Both were taken to John Muir Medical Center in Walnut Creek.

The crash closed the freeway for more than an hour, the CHP said.

Anyone who witnessed the collision is asked to call the Dublin office of the CHP at (925) 828-0466. The crash remains under investigation.