CHICAGO (CBS) — All northbound lanes of the Dan Ryan Expressway were closed Sunday morning as Illinois State Police investigated a reported shooting.

Troopers responded to a local hospital after a walk-in gunshot victim said he had been shot on Interstate 94 near 75th Street shortly after 2 a.m. The 31-year-old man was in the back seat of a vehicle that was shot at, and his injuries were not life threatening. A driver and another passenger were not injured, ISP said.

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Shortly after 4:30 a.m. ISP closed all northbound lanes of the expressway for the investigation. Traffic was diverted at 87th Street, and ramps including the exit ramp at 76th Street, the exit ramp to 71st Street, the ramp from 75th Street to I-94 northbound and the ramp from 79th Street to I-94 north were closed. All lanes and ramps were reopened to traffic shortly before 8 a.m.

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The investigation is ongoing.

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Anyone who witnessed the shooting or has any information to share is asked to contact ISP at (847)294-4499. Callers can remain anonymous.