Three men were killed early Saturday when the car they were in veered across several lanes of southbound Interstate 5 near San Clemente and smashed into a tractor-trailer parked on the shoulder of the freeway.
The Orange County coroner's office withheld the victims' names until their families could be notified.
A fourth man in the car, Estaban Delgado, 33, of Arleta, remained in critical condition at Mission Hospital Regional Medical Center in Mission Viejo, hospital spokeswoman Terri Castillo said.
The driver, authorities said, apparently lost control of the 1979 Pontiac at about 4 a.m., striking the rig near the Camino De Estrella overpass.
The truck's driver had stopped to check his load and was outside the truck when the accident occurred, according to Robyn Ferrin, a spokesman for the California Highway Patrol. The driver was not injured.
The three men killed, who all died at the scene, were the driver, 21, of Sylmar; a 24-year-old passenger from San Fernando, and a 26-year-old from Arleta.