(Reuters) - A high-speed pileup of up to 150 vehicles on a fog-bound Texas interstate highway killed at least two people on Thursday and injured up to 100, a sheriff's spokesman said.

The chain reaction of collisions shut down Interstate 10 about 15 miles west of Beaumont for several hours, said Deputy Rod Carroll of the Jefferson County Sheriff's Office.

"We have 18-wheelers on top of cars, we have cars on top of cars. It's just catastrophic," he said, adding that rescuers were still looking for victims.

Two bodies were found underneath a tractor-trailer, he said. After all vehicles were searched, authorities determined as many as 100 people were injured, up to 12 of them seriously or critically hurt, Carroll said.

"People were not driving for the conditions at hand," he said.

He said the initial accidents took place separately about a mile apart on the east- and westbound sides of the interstate.

The highway had been crowded with motorists traveling over the Thanksgiving holiday. Many of the vehicles were moving close to the posted speed of 70 mph despite dense fog that limited visibility, Carroll said.

The westbound lanes of the interstate have been reopened, he said.

(Reporting by Ian Simpson in Washington; Editing by Sandra Maler and Todd Eastham)