UPDATE (2 p.m.) - The California Highway Patrol says a 21-year-old Campbell man sustained major injuries in a crash Monday morning near Atascadero.
Officers say the driver was heading southbound on Highway 101, north of the San Ramon offramp, when, for unknown reasons, his vehicle went off the road and rolled.
A witness tells KSBY News she heard the crash from her house and called 911 at about 1:40 a.m. She says she saw an officer drive by a short time later but then heard what sounded like screams coming from the area at around 3 a.m.
The witness says she and her husband went to check things out and followed skid marks into the creek where they found the wreckage and reportedly made another call to 911 around 3:30 a.m.
She says her husband worked to keep the injured driver awake until first responders showed up.
An updated on the man's condition was not immediately known.
CHP says drigs or alcohol do not appear to be factors in the crash.
ORIGINAL STORY: California Highway Patrol and Cal Fire responded to a single-vehicle crash on Highway 101 south at Vineyard Drive near Templeton.
Police say a car drove 50 feet off the side of the road and into the riverbed.
One man was found outside of the vehicle unconscious with major injuries. Police say he was transported to a hospital.
Cal Fire responded to the crash due to reports of a possible ruptured gas line in the area.
A gas company was called to evaluate the possible rupture.
There is no word yet on whether the line ruptured.
CHP did not say whether alcohol or drugs were a possible factor in the crash.