What caused 20 vehicles to get flats on I-294 Friday morning? State police aren't sure

About 20 vehicles on Interstate 294 near Des Plaines were disabled by flat tires Friday morning, possibly after running over large chunks of ice or concrete, police said.

Reports started coming in about 5:45 a.m. All the cars were headed north near Touhy Avenue, and all the damage occurred before Illinois State Police troopers showed up about 6:05 a.m., state police Master Sgt. Anton Manuel said.

The motorists reported hitting large pieces of debris in the roadway, Manuel said. Because it was dark, they weren't sure what they hit, but some thought it was ice or concrete, he added.

If it was ice, it may have come off the top of a semitrailer truck traveling down the highway, Manuel said.

Remarkably, all of the drivers safely got to either the left or right shoulders of the highway, and the morning traffic flow wasn't affected, Manuel said.

Some were able to change damaged tires and drive on. But a dozen motorists needed assistance, Manuel said.

Des Plaines resident Lukasz Switaj had just picked up his mother at O'Hare International Airport and was headed to her home in Niles shortly after the motorists experienced flats. He got through the area without any problems but saw about 10 cars grouped together on the right shoulder of the highway and others scattered on both shoulders.

"Some people were out checking their cars," he said. "My mom thought it was an accident, but it didn't make any sense to me because they weren't damaged and all of them were on the shoulder."

State troopers and Illinois Tollway maintenance workers scoured the area for signs of what caused the damage, but no debris was found.

"They were unable to locate anything," Manuel said.

Whatever was in the roadway may have been crushed by passing cars or pushed off the side of the highway, Manuel said.

Police don't suspect foul play.