The crash occurred on Interstate 15, just outside of the city of Ontario, on a congested section of freeway near a construction zone, according to the San Jose Mercury News. Investigators are still trying to determine a cause for the pileup, which involved several cars and three semi trucks.
Two adults and two children were killed when their car caught fire after being pinned between two of the trucks, according to Jeff Briggs, an officer with the California Highway Patrol who responded to the incident.
Three other people were injured in the incident, Briggs told the Associated Press, and all fatalities were pronounced dead on the scene. The names of the victims of the crash have yet to be released.