Six people are dead in a Montana highway pileup Friday that may have been caused by a dust storm, authorities said.
A series of collisions involving 21 vehicles happened on Interstate 90 near Hardin, Montana Highway Patrol Sgt. Jay M. Nelson said by email.
"A quick-arising dust storm caused a 21-vehicle incident this evening," he said.
Two children were among those killed. Further details were not immediately available.
Eight people were hospitalized, according to highway patrol. Their conditions were not provided.
It took more than six hours to fully reopen the highway. Nelson said authorities were dealing with "a lot of debris and complete chaos."
All eastbound traffic was diverted off the highway, and westbound traffic was reduced to one lane, according to the Montana Department of Transportation, which first reported about the pileup near mile post 493 at 4:55 p.m.
"I'm deeply saddened by the news of a mass casualty crash near Hardin," Gov. Greg Gianforte tweeted. "Please join me in prayer to lift up the victims and their loved ones. We're grateful to our first responders for their service."
There were thunderstorms over Billings, a city around 40 miles west of Hardin, and an "outflow" which sent strong winds toward Hardin, said National Weather Service meteorologist Todd Chambers.
“The winds outran the thunderstorm,” Chambers said.
The winds picked up dust and a gust of 64 mph was recorded near Hardin, he said. Visibility measured around a quarter of a mile.
The National Weather Service had issued severe thunderstorm watches and warnings for south central and southeastern Montana Friday.