The driver of a dark-colored sedan was pronounced dead after the car crashed into the center divider while on the HOV transition from the northbound 405 Freeway to the northbound 605 Freeway in Los Alamitos, authorities said.
The crash was reported to the California Highway Patrol at 11:46 p.m. on Monday.
The car became fully engulfed in flames but arriving officers were able to get the driver out, the CHP said. The driver was unconscious and not breathing.
There was no information about the age and gender of the driver or whether there were passengers.
Caltrans shut down the HOV transition for the CHP investigation.