Sgt. Cindy Guerra said the officer was in his personal vehicle in the 3600-block of South Prairie Avenue at about 7 p.m. when two people approached.
"Two offenders approached, one to the driver's side and one to the passenger side. The offender on the passenger side tapped the window to try to distract the off-duty officer while the offender on the driver's side announced a robbery," Guerra said.
The off-duty officer shot the offender who announced the robbery once in the abdomen. The second offender escaped on foot and remains at large, police said.
"Unfortunately the person that did it got shot, but you gonna learn a lesson from that. You carjacked the wrong one," said Darlene Amao, witness.
The offender, who police said is a juvenile, was taken to Northwestern Memorial Hospital in stable condition. The off-duty officer was taken to Rush University Hospital for a routine stress check, Guerra said.
Police went door-to-door in the area, looking for witnesses and surveillance video.
The officer is an 18-year veteran of the force.
"It shows how brazen these offenders are, they'll target anyone, and tonight it just happened to be one of our own," Guerra said.
Police Involved Shooting - 3600 S. Prairie. An individual attempted to carjack an off duty CPD officer and was shot during the encounter. Offender transported to Northwestern in serious condition. No injuries to officer. PIO responding pic.twitter.com/HHLKWaeRku— Anthony Guglielmi (@AJGuglielmi) December 19, 2017