It happened just before 10 p.m. on the 5100 block of Springfield Avenue.
Police say a 30-year-old man was found shot in the neck on the third floor.
A 27-year-old woman who lives there had a protection-from-abuse order against the man.
Investigators say the man had arrived at her home, and they got into a physical struggle.
That's when they say the woman fired two shots.
The man was taken to Penn Presbyterian Medical Center. He's listed in critical condition.
The incident remains under investigation.