Six people have died after a dust storm fuelled by wind gusts topping 60mph caused a pile-up in the US state of Montana.
Twenty-one vehicles crashed on Interstate 90, three miles west of Hardin, and Montana Highway Patrol Sergeant Jay Nelson said authorities believe the weather was the cause.
“It appears as though there was heavy winds, causing a dust storm with zero visibility,” he said.
While the highway patrol did not have an immediate count of the number of injuries, Sgt Nelson said additional ambulances had to be called in from Billings to help.
State governor Greg Gianforte said on Twitter: “I’m deeply saddened by the news of a mass casualty crash near Hardin. Please join me in prayer to lift up the victims and their loved ones. We’re grateful to our first responders for their service.”
Montana attorney general Austin Knudsen, who oversees the highway patrol, said in a statement: “The Montana Highway Patrol is on the scene with other first responders and investigating the incident.
“We will release more information as it becomes available and is appropriate out of respect of the lives lost and their loved ones.
“My prayers are with everyone affected by the tragic events during the dust storm in Big Horn County today.”
A video from the Billings Gazette showed hundreds of lorries, camper vans and cars backed up for miles along the two eastbound lanes of the road.
The dust storm’s roots can be traced back several hours, when storms popped up in central southern Montana and slowly began moving east, according to Nick Vertz, a National Weather Service meteorologist in Billings.
The storms prompted a severe thunderstorm watch that covered Hardin and other parts of Montana. Meteorologists forecast the potential for hail, scattered wind gusts up to 75mph and frequent lightning.
A so-called “outflow” — or a surge of wind which is produced by storms but can travel faster than them — flew east-south-east about 30 miles ahead of the storms, Mr Vertz said.
A 40mph gust of wind was recorded at nearby Big Horn County Airport at 4.15pm, and the crash was reported to the highway patrol at 4.28pm.
By the airport weather station’s next reading at 4.35pm, the gusts had picked up to 62mph. Another reading 20 minutes later recorded a gust of 64mph.
The wind picked up dust and reduced visibility to less than a quarter of a mile.
