ISP said troopers responded to eastbound Interstate 290 at Austin Avenue in Oak Park just after 1:45 p.m. for a report of a shooting. No injuries have been reported.
Chopper 7 was over the scene, where investigators could be seen canvassing the area for evidence.
Inbound traffic was being diverted off Harlem Avenue and being let back on at Austin Avenue. All lanes have since reopened.
ISP asked anyone with information to contact them at 847-294-4400 or ISP.CrimeTips@Illinois.gov. Witnesses can remain anonymous.
Authorities did not immediately provide further information about the shooting.