A deadly dust storm in southern Illinois caused numerous crashes on Interstate 55 on Monday, leaving at least 6 people dead and dozens more hospitalized.

Two of the accident victims were still unidentifiable as of Tuesday afternoon. Another 37 people were injured and taken to area hospitals, some with life-threatening injuries.

It happened along a 2-mile stretch of the highway as 45-mile-an-hour winds stirred up clouds of dust leading to “zero visibility.”

State police said as many as 60 cars, trucks, and multiple tractor-trailers were involved in the pileup. Accident survivor Tom Thomas, 43, said that after the vehicle he was in got into a crash, the only thing he could hear “was crash after crash after crash behind us.”

More than 40 troopers were sent to the scene, including members of the state police crash reconstruction team. Illinois Governor J.B. Pritzker described the scene as “horrific.”

“They were very unusual circumstances. Certainly, dust storms happen, but it is not something that happens every day here in this part of Illinois or any part of Illinois,” Illinois State Police Director Brendan Kelly said at a news conference Tuesday.

The National Weather Service said most of the dust came from newly plowed fields.