The shooting happened just before 8:00 p.m. Tuesday in the 100 block of Girard Avenue.
Police say the 26-year-old victim, described as a transgender woman, was in a third floor apartment and went downstairs to answer the door.
Sources say, the victim was expecting someone. However, police say the victim did not recognize the man at the door.
According to police, that suspect forced his way up the stairs and into the victim's third floor apartment.
He hit the victim once in the head with a gun, then shot the victim in the head at least once.
Neighbors said they did not hear any commotion, but police described a gruesome scene, saying there was blood throughout the victim's apartment.
Police have no motive so far for the crime, but they are hoping area surveillance cameras can help them put the pieces together.
The identity of the victim has not been released.
While the victim was listed in critical condition at Hahnemann University Hospital, the victim is expected to survive.