The accident happened near Pittsfield this morning, sparking a fire that closed traffic in both directions.
Illinois State Police Master Sergeant Mark Welch says road crews were setting up cones when a westbound truck slammed into the back of the trucks.
The trailer carrying sodium nitrate and sodium hydroxide then hit the side of the Twin Eagle Bridge and caught on fire, sending smoke into the air.
Welch says four construction workers and the driver of the truck were injured in the accident.
An Illinois Department of Transportation spokesman says traffic has been detoured to U.S. 54 and State Routes 106 and 100.
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