The crash happened just after 10:20 a.m. in the northbound lanes of I-57 near 107th Street in Morgan Park.
"I kept hearing the ambulance, police helicopters in the area, and I I didn't know what was happening. I just came down there," resident Londell Williams said.
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For a time, northbound traffic was only getting through on the far left lane.
"When I came, there was a lot more traffic out here, trucks knocked over and the side," resident Patricia Wilson said.
The trooper was taken to a local hospital with non-life threatening injuries.
"I know the paramedics were down there. And when I walked away, they were pulling out the gurney to put someone on," motorist Dedric McCullough said.
Police did not immediately provide any identifying information regarding the trooper, nor details about the vehicle that hit him.