Officials are investigating a 35 vehicle pileup that killed two people in Kern County, California, over the weekend.

The crash occurred around 7:30 a.m. on Saturday, January 6, amid dense fog west of Bakersfield.

Police say that 17 passenger vehicles and 18 semi trucks collided on southbound I-5. Thirty-five total vehicles were involved.

Two people died in the crash. Nine others suffered minor to moderate injuries.

“All the witnesses have fog visibility at approximately 100 feet at the time, so there was heavy fog at the time of the collision,” CHP Buttonwillow PIO Manny Garcia told Bakersfield Now.

Jim Calhoun with the Kern County Fire Department told KGET that visibility was as low as 10 feet when firefighters responded to the “chaotic” crash scene.

Southbound I-5 was closed for most of the day on Saturday, but has now reopened.