Police on patrol just before midnight Sunday heard gunshots fired, drove toward the spot of the gunfire, and pursued a vehicle driving away.
Several shots were fired from the car which struck the pursuit vehicle, injuring one of the officers. The officers did not return fire.
The injured officer was initially taken to Memorial Hospital of Carbondale where he was treated for a gunshot wound before being transferred to a St. Louis-area hospital. Carbondale is around 95 miles southeast of St. Louis, Missouri.
The investigation, which is ongoing, is being led by the Illinois State Police.
By Euan McKirdy and Joe Sutton