Six people killed as dust storm causes US highway pile-up

First responders work the scene on Interstate 90 after a fatal pileup where at least 20 vehicles crashed near Hardin, Mont., Friday, July 15, 2022. (Amy Lynn Nelson/The Billings Gazette via AP)

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.