BAKERSFIELD, Calif. (AP) — A crash involving dozens of vehicles along a foggy stretch of California’s Interstate 5 in southern California has left two people dead and nine others injured.

The pileup involving 35 cars happened around 7:30 a.m. Saturday west of Bakersfield, according to authorities. Kern County Fire Department spokesman Jim Calhoun told reporters that visibility was roughly 10 feet when crews arrived to the “chaotic” scene.

The crash, spread over about half a mile (0.80 kilometers), involved 17 passenger vehicles and 18 big rigs. Two people were pronounced dead at the scene and nine others were hospitalized with minor injuries, authorities said.

“It was pretty chaotic when I first pulled up at the scene, it was compressed natural gas, saddle tanks on the side of some the big rigs that were ruptured, so a lot of the bystanders that weren’t injured were trying to help people and were in a plume of natural gas so we had to deal with that first and get everyone evacuated from that area,” Calhoun told KBAK-TV on Saturday.

The California Department of Transportation, or Caltrans, said Saturday that southbound lanes would remain closed overnight while crews cleaned up debris and determined an official cause of the crash.

A message left Sunday with Caltrans wasn’t immediately returned.