Two people died and dozens were hurt when around 100 vehicles collided on a Texas highway in dense fog, leaving trucks twisted on top of each other and authorities rushing to pull survivors from the wreckage.
"It is catastrophic," said Jefferson County sheriff's office deputy Rod Carroll, on Thursday. "I've got cars on top of cars."
The Thanksgiving holiday morning crash happened on Interstate 10 about 128 kilometres east of Houston.
At least 51 people had been taken to area hospitals and at least eight were critically hurt, officials at Acadian Ambulance service told KFDM-TV.
It wasn't immediately clear how the pileup began, but Carroll said the fog was so thick that officers didn't immediately realise they were dealing with multiple accidents.
I-10's eastbound lanes were expected to remain closed for most of Thursday.
Texas Department of Public Safety trooper Stephanie Davis told KFDM that two people were killed in an SUV crushed by a tractor trailer. She said at least 100 cars and trucks were involved in the accident.
Carroll said uninjured drivers tried to help as authorities sorted through the wreckage.
"It's just people helping people," Carroll said. "The foremost thing in this holiday season is how other travellers were helping us when we were overwhelmed, sitting and holding, putting pressure on people that were injured."