CHICAGO (WGN) — An off-duty Chicago police officer fatally shot another off-duty officer Tuesday night, sources told WGN.

The Chicago Fire Department confirmed one person was shot in a home in the Far Northwest Side around 7:15 p.m. Tuesday.

Sources told WGN that the incident was domestic and involved an off-duty female officer and an off-duty male officer. According to multiple sources, the woman shot the man. More details surrounding the shooting are still unknown.

The male officer was taken to Lutheran Hospital in critical condition after being shot in the chest. He later died. He was 44 years old.

Police have not said whether the woman was taken into custody.

Local detectives and the Civilian Office of Police Accountability (COPA) are investigating.