The incident happened just before 10:30 p.m. Tuesday at the Olympic Gardens Apartments in Whitehall Township.
Investigators said a 34-year-old man shot his 27-year-old girlfriend before turning the gun on himself.
Authorities said the man called 911 and reported that he had shot his girlfriend before shooting himself.
The man died from his injuries, while the woman was seriously injured, according to investigators.
Authorities have not yet released the man's identity.
The incident remains under investigation.