At least six people have been killed after a dust storm caused a pile-up of 21 vehicles in Montana.
Strong winds whipped up the dust and left drivers with “zero visibility” before the “mass casualty crash” on Friday afternoon.
Gusts of 60mph were recorded around the time of the pile-up on the Interstate 90 highway near Hardin, a city in the state’s south.
It is not clear how many were injured in the incident but a highway patrol official said extra ambulances had to be called in from another city to help.
Cars could be seen crashed into a grassy ditch off the highway while emergency services attended the scene on Friday afternoon.
Dozens of other vehicles were backed up along Interstate 90.
The crash was reported to highway patrol at 4.28pm local time on Friday.
Minutes after the crash, the nearby Big Horn Country Airport recorded a wind speed of up to 62mph - up from 40mph less than a quarter of an hour before.
The wind easily picked up dust, a product of recent scorching temperatures over the last week.
“It appears as though there was heavy winds, causing a dust storm with zero visibility,” Jay Nelson from Montana’s Highway Patrol said.
Visibility is believed to have dropped to less than 400 metres in the bad weather conditions on Friday.
Greg Gianforte, the governor of Montana, said he was “deeply saddened” by the news of the “mass casualty crash”.
“Please join me in prayer to lift up the victims and their loved ones. We’re grateful to our first responders for their service,” he added.
Additional reporting by Associated Press
