MICHIGAN CITY, Ind. — Work continued Friday morning to remove wreckage on a busy interstate that connects Chicago to Detroit that was blocked by a massive pileup involving more than 40 vehicles, many of them semitrailers.

Three people died and more than 20 were injured — including one critically — in the crash Thursday on a snowy stretch of eastbound Interstate 94 in northwestern Indiana. At least one person was trapped in a vehicle for hours before authorities could come to the rescue, Indiana State Police said.

Snow and whiteout conditions were contributing factors, state police said. A band of heavy lake-effect snow was reported Thursday afternoon when the pileup began, dropping 1 to 2 inches of snow per hour and reducing visibility to a quarter-mile or less, National Weather Service meteorologist Evan Bentley said.

The eastbound lanes of I-94 were closed through the night as cranes and wreckers helped clear the scene. State police Cpl. Daniel Becker said the eastbound lanes remained closed Friday morning and it could be several more hours before the numerous semitrailers and other vehicles would be cleared.

State police scheduled a news conference later Friday morning during which officials expected to release identities of the victims.

Photos showed semitrailers and mangled passenger vehicles jammed together the width of the highway near an overpass. Some passenger cars were sandwiched in the wreckage. I-94 is a main highway heading east from Chicago to Michigan and Indiana, and the crash happened near Michigan City, about 60 miles from Chicago.

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 the highway. A woman in the car next to hers noticed she had children with her and offered cereal, popcorn and fruit to tide them over.

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. … We were pretty nervous.”

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 were taken to IU Health LaPorte Hospital, a nursing supervisor said. Porter Regional Hospital also received patients, Wojas said.

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.