The pileup on Interstate 94 eastbound began Thursday afternoon near Michigan City, about 60 miles from Chicago, according to Indiana State Police, and at least one person was trapped in a vehicle for hours.
I-94 is the main highway heading east from Chicago to Michigan and Indiana, and the main thoroughfare between the nation's third-largest city and Detroit. Traffic was backed up for hours in frigid snowy conditions, though state police said one westbound lane was open late Thursday.
Photos of the scene showed semitrailers and mangled passenger vehicles jammed together the width of the highway near an overpass. Some passenger cars were sandwiched in the wreckage.
National Weather Service meteorologist Evan Bentley said a band of heavy lake-effect snow was reported in the area at the time of the crash, dropping 1 to 2 inches of snow per hour and reducing visibility to a quarter mile or less - with some reports of visibility near zero.
Scott Collins, 17, of Chesterton, Ind., 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."
He said a box truck got stuck on a guardrail and nearly went over into a waterway.
"We were pretty nervous," he said.
Indiana State Police Sgt. Ann Wojas said 20 to 30 people were injured, including one with life-threatening injuries and another who was flown by medical helicopter to a hospital.
Franciscan St. Anthony Health in Michigan City had received at least 10 patients, hospital president Dr. Jim Callaghan said. Six people from the accident were taken to IU Health LaPorte Hospital, a nursing supervisor there said. Porter Regional Hospital also received patients, Wojas said.
The eastbound side was expected to be closed overnight as cranes and wreckers helped clear the scene, police said.
Drivers stuck in the backup could only wait and try to stay warm as temperatures hovered around 10 degrees.
Stacey Johnson, 37, had a family emergency and was traveling from western Michigan to Tennessee with her three sons, ages 3, 9 and 10. She told The Associated Press she'd researched road conditions before leaving because she was worried about the weather. She didn't know about the accident until traffic started crawling and then stopped.
Nearly five hours later, long after she'd planned to stop for dinner, her car was still sitting on the westbound side of highway. A woman in the car next to hers noticed she had children with her and offered cereal, popcorn and fruit to tide the family over.
Police said city buses were brought in to warm stranded motorists and transport the injured, though Johnson said she hadn't seen them. But she felt fortunate that she'd gotten gas before leaving Michigan.
"If it weren't for the fact that I have a full tank and a safe car, this could be a really dangerous situation," she said.