Scott Collins, 17, of Chesterton, told The Associated Press he was riding in a car with three other teens and saw the crash happen just behind them.

"One of the semis started sliding and I think it jackknifed in the middle of the road" and collided with another semi, he said. "After that happened, multiple semis locked up."

A truck got stuck on a guardrail and nearly went into a waterway, he said.

"We were pretty nervous," he said.

Indiana State Police said the eastbound lanes of I-94 are expected to remain closed until Friday. The westbound lanes were scheduled to reopen by late Thursday.

By 9:40 p.m., officials were beginning to tow vehicles from the scene. The American Red Cross and a bus provided by Michigan City police were on the scene to keep people warm.

Troopers estimate there were about 46 semitrucks and vehicles involved in the crash, with the majority being semitrucks. However, state police said it could take until Friday morning to have a complete tally.