Detectives believe the wrong-way driver may have been under the influence - but an official cause has not been released.
MADERA COUNTY, Calif. (KFSN) -- Authorities have identified the man killed in a crash in the Madera Ranchos area on Sunday as 50-year-old Walter Cleven Vayson, Jr. of Oakland.
The California Highway Patrol says the deadly crash happened just as the thick Valley fog blanketed the roadways just after midnight.
The CHP says a gray Toyota Rav 4 was traveling toward incoming traffic on Avenue 12, near Road 36 1/2.
The Toyota crashed head-on with a white BMW.
Officers arrived to find the wrong-way driver, Vayson, not wearing a seatbelt.
Vayson died at the scene.
Detectives believe he may have been under the influence - but an official cause has not been released.
The dense fog would make it difficult for drivers to see the road ahead.
"Fog may have played a part, or a contributing factor in the crash. Upon officers' arrival, the fog conditions were anywhere from 100 to 500 feet visibility," said Sgt. Taka Hiura with the CHP.
The other vehicle involved in the crash had four people inside, including an adult woman, and three underage passengers.
They are now hospitalized, but officials say they should recover from their injuries.
RELATED: Know the Road with the CHP: How can I stay safe in the fog?
The CHP says driving in the fog can be dangerous and it's important to be adjust to the road conditions.
"Drive with lights on low beam, not on high beam at all, and reduce speed drastically during foggy conditions," said Sgt. Hiura.
Here are some other things to keep in mind when the fog rolls in: