Indianapolis police identified the officer in custody as 42-year-old Adrian Aurs.
Both Aurs and the victim worked at the Indianapolis Metropolitan Police Department, where Aurs is an 18-year veteran, said Sgt. Kendale Adams.
Around 8 p.m. Friday, officers responded to a call from Aurs’ estranged wife about domestic violence, he said.
After the initial visit from officers, a special investigations unit detective was sent to do follow-up work at the scene because it involved the wife of a police officer.
The SIU unit investigates criminal complaints or criminal allegations involving police officers and other public safety officials in the city of Indianapolis.
While the detective was at the scene at around 10:30 p.m., Aurs “re-emerged and engaged in gunfire,” Adams said. One of the bullets struck the detective in the elbow.
The detective returned fire, but missed, police said. Aurs then fled in his personal car. His estranged wife and children were inside the apartment when the shooting occurred, but they were not injured.