A search is underway for a man accused of shooting a DeKalb County, GA, police officer multiple times after fatally shooting his girlfriend. The suspect has been identified as 27-year-old Otis Walker.

According to DeKalb police, officers were ambushed while responding to a domestic call at a home in the Stonecrest area. They were “immediately fired upon” by someone hiding between two homes, Maj. Jerry Lewis told Channel 2 Action News from the scene.

A neighbor driving by heard the gunshots and saw the officer, identified by police as three-year veteran Derek Nunn, go down.

“That’s when I put my car in park and was helping that officer,” Cleveland Dollison told the news station. “They laid him down in the neighbor’s yard, (the neighbor) came out, we got towels, and we just tried to help, do what we could.”

Dollison said he helped to apply a tourniquet to the officer’s leg. Nunn had surgery and is recovering at a hospital Thursday afternoon, police told the Atlanta Journal-Constitution.