A Santa Rosa man was killed when the car he was driving veered across Arnold Drive west of Sonoma and struck a power pole, the CHP said Sunday.
The man's identity was not released Sunday pending notification of his relatives.
Saturday's crash at the intersection of Arnold Drive and Verano Avenue occurred at about 6:30 p.m.
Napa CHP Officer Kiuya Brown said the Nissan sedan was heading north on Arnold when for unknown reasons the vehicle swerved into the oncoming lane and collided with the power pole.
The crash sheared off power lines and dumped oil from a transformer onto the car, causing the engine to start smoking but not catch fire, Brown said.
He said emergency responders had to wait for PG&E to declare the area safe before they could administer aid to the driver. He was pronounced dead at the scene.
The CHP was investigating whether the man may have suffered a medical ailment prior to the crash. Drugs and alcohol were not suspected, Brown said.