Fallbrook, CA -An adult and a young child riding in the same car died in a three-vehicle traffic collision Sunday on southbound Interstate 15 south of State Route 76.

Several others were transported to the hospital, one with major injuries and three with minor injuries, said Capt. John Choi of the North County Fire Protection District.

The 3:14 p.m. Sunday crash involved a black Toyota Tacoma pickup, white Tesla and a black Kia Forte, according to the California Highway Patrol.

The people who died were a 29-year-old and a 4-year-old, both from San Marcos. It’s not clear yet if the pair were related.  

The pickup, which was driven by a 23-year-old man from Oceanside, was headed north on Old Highway 395 when he it left the roadway, through a chain-link fence and landed on its roof on the I-15. The man was hospitalized with life-threatening injuries, according to the CHP.

The cause of the crash is still under investigation, according to the CHP. It’s not known if drugs or alcohol played a role in the crash

The San Diego County Medical Examiner’s Office was called to the scene at 3:37 p.m., the CHP reported.

At one point, all lanes of southbound I-15 south of Mission Road in Fallbrook were blocked. Drivers on both southbound and northbound I-15 were stuck in hours-long traffic after the crash. All lanes were reopened by 11 p.m. Sunday.