A motorist died after his car collided head-on with an Edison construction truck and slid off the steep canyon road shortly before 4 p.m., Sheriff's Sgt. Fray Lupian said.
The Edison driver walked away from the accident, Lupian said.
Rescuers searched for two hours but found no other survivors, Lupian said.
The name of the 56-year-old male driver who died was not immediately released.