The LA County coroner has identified the man killed Wednesday after his pickup truck collided with a big rig on Interstate 5, near Castaic, as 35-year-old Sergio Martinez of Grand Junction, Colorado.

Officials with the Los Angeles County Department of Medical Examiner-Coroner’s Office released the identity over the weekend.

The official cause of the man’s death has not yet been established, according to Sarah Ardalani, spokeswoman for the department, pending additional investigation in the case.

The Grand Junction resident was pronounced dead early Wednesday, following a traffic collision in the northbound lanes of I-5, just north of Hasley Canyon Road.

He was the driver of a pickup truck that ran into the back of a tractor-trailer.

“The pickup truck was lodged under the truck-tractor combination and burst into flames,” Officer Josh Greengard of the California Highway Patrol said Wednesday. “The pickup truck had a solo driver, who sustained fatal injuries.”

Although firefighters were cleared from the crash scene at 6:45 a.m., they were called back to the scene two hours later “to extricate the patient for the coroner,” Brian Stevens, spokesman for the Los Angeles County Fire Department, said Wednesday.