(CBS) – Fog and low visibility was blamed for two pileups on Interstate 57 Thursday evening that injured motorists and snarled traffic in Will County.

The line of cars parked on northbound I-57 waited patiently as emergency crews worked to clean up and piece together two crashes that led to pileups.

State police say the crash in the northbound lanes occurred around 4:40 p.m. and involved seven semis as about 12 passenger vehicles. At least one tractor semi-trailer ignited, but no hazardous material was involved.

Some 10 motorists were transported to area hospitals with non-life-threatening injuries, state police said.

Motorist Joan Wallis was witness to the aftermath. She described cars stuck under semi-tractor-trailer trucks.

“The cars themselves were pretty much intact. It was just crushed front ends and things like that,” she told CBS 2’s Courtney Gousman.

Wallis, a nurse, says she was “delighted” no one appeared to be seriously injured.

Once police and fire arrived, Wallis continued southbound, and she encountered a second crash.

Illinois state police say dense fog was to blame for the crashes.

“You couldn’t see anything,” Wallis says.

Some northbound lanes remained closed late Thursday.