HARDIN, Montana (AP) — At least five people have died after a pileup Friday evening on Interstate 90 in Montana, authorities said.

At least 20 vehicles crashed and Montana Highway Patrol Sgt. 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, Nelson said additional ambulances had to be called in from Billings to help.

Gov. 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.”

The incident happened 3 miles (5 kilometers) west of Hardin around 4:30 p.m.