Witnesses say the officer was involved in a shootout with a teenage suspect, who was also shot, near 111th and Loomis in the city's Morgan Park neighborhood.
Both the officer, who was shot in the knee, and the suspect are being treated in the hospital. The officer is stable condition and the suspect is in serious condition.
A second suspect is in custody and police are looking for a third suspect.
"Just heard about 15 gunshots. Came outside and it looks like a scene out of the Blues Brothers. The police responded immediately," said Phillip Jackson, resident.
Superintendent Garry McCarthy was at Christ Hospital late Wednesday evening, checking on the officer's condition.