Chopper7 was over the scene around 4 p.m. in the southbound lanes of I-294 near 75th Street in south suburban Countryside.
Illinois State Police said the incident began around 3 p.m. and deferred questions to the DuPage County Major Crime Unit.
Illinois State Police did say its troopers are handing a crash involving a truck tractor semi-trailer and an Oak Brook Police Department squad car.
No injuries have been reported.
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Drivers are encouraged to seek alternate routes, as traffic in that area is backed up.
This is a breaking news story. Check back for updates.
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