The ambulance carrying the officer arrived at Northwestern Memorial Hospital late Sunday night, ahead of him a procession of Chicago Police officers clearing the way for the officer.
Sources say the 42-year-old officer was initially taken to Advocate Trinity Hospital following the shooting, but was stabilized enough to transfer him to Northwestern Memorial.
Upon arrival and seen through the ambulance window, the officer appeared to be conscious, but the police department has yet to make any official statements about what happened, so while the circumstances surrounding the shooting are unknown, sources tell ABC7 Eyewitness News that the shooting happened around 8:45 p.m. Sunday.
Those sources also say that four people are in custody and being questioned.
Chicago Police Superintendent Garry McCarthy arrived at Northwestern Memorial ahead of the ambulance Sunday night.
The officer was apparently shot on the bridge of his nose, but we are told he was able to speak following the shooting.
Check back with ABC7Chicago.com for further details on this developing story.
(Sun Times Media Wire contributed to this report.)