The Chicago Office of Emergency Management and Communications tweeted out the lane closures just after 6:30 p.m.
Illinois State Police said they responded to the area for a report of shots fired. State police said one victim was taken to an area hospital with injuries. Chicago Fire Department officials said an adult was shot and taken to Mt. Sinai Hospital in critical condition.
Three and a half hours after the shooting was reported, a large police presence remained along that mile-long closed stretch of I-55. Deputies were seen walking the expressway with flashlights, searching for shell casings or any other evidence.
Two damaged cars could be seen on the side of the road surrounded by police. Traffic was backed up for a mile, and traffic is being diverted off the expressway at Pulaski.
Drivers should seek an alternate route.
No further information was available, state police said.