The crash on Interstate 90 outside Hardin, Mont., a town of 3,800 about 50 miles east of Billings, involved 21 vehicles, including six semi-trucks, Sgt. Jay Nelson, a spokesman for the Montana Highway Patrol, said in an interview. It was not immediately clear how many people were injured, he said. Authorities did not immediately release the names or ages of the victims. “All indications are that there was an isolated weather event that caused near blackout conditions at this location,” Sergeant Nelson said. “A dust storm in the area with extremely strong winds is the preliminary cause of the crash.” By Friday afternoon, storms in the area had produced strong, strong winds known as outflows, which travel about 30 miles ahead of storms, said Nick Vertz, a meteorologist with the National Weather Service in Billings. By late afternoon, there were wind gusts of 62 miles per hour that kicked up dust and reduced visibility to less than a quarter of a mile, he said. Typically, the wind gusts produced by these storms are 30 to 40 miles per hour, Mr. Vertz said. The crash, which happened around 4:30 p.m., backed up traffic on Interstate 90 as the highway patrol investigated. As of about 9 p.m., the eastbound lanes were still closed and officials were diverting traffic. Gov. Greg Gianforte said late Friday on Twitter that he was “deeply saddened by the news of a mass crash near Hardin.” “Please join me in prayer to lift up the victims and their loved ones,” he said. “We are grateful to our first responders for their service.”
