Crews are clearing away the last semi-truck from a deadly pileup on Interstate 94 near Michigan City, Ind.

Three people are confirmed dead after the 40-car crash last night. One person is being treated for life-threatening injuries and another 20 were hurt in the accident.

The crash occurred amid blowing snow that made it very difficult to see.

Indiana State Police Sergeant Todd Ringle said investigators aren’t sure yet what caused the crash, but he said conditions were so bad that even one vehicle slowing down suddenly could have caused the chain reaction pileup.

Ringle said they hope to reopen the highway sometime this morning, but he couldn’t guess what time that would be.

Patrick Smith is a WBEZ producer and reporter. Follow him on twitter @pksmid.