A 26-year-old woman was shot in the head by an assailant at her apartment Tuesday night near Northern Liberties, police said.

The victim, who is transgender, was reported in critical but stable condition at Hahnemann University Hospital. She was able to speak and told officers she did not know the perpetrator, whom she described as a man in his 20s, police said. The motive was unknown.

At 7:44 p.m., a caller to 911 reported that a person in the 100 block of West Girard Avenue needed medical help. A doctor at Hahnemann later determined she had been shot behind the left ear.

The woman told police she was expecting a visitor when the man appeared and pointed a gun at her. She was pistol-whipped, then shot in her third-floor apartment, police said.

The woman did not know if anything was stolen during the attack, police said.

Police recovered a spent shell casing in the apartment. Detectives were expected to review video from nearby cameras, including one operated by the police on Girard Avenue.

Contact Robert Moran at 215-854-5983, bmoran@phillynews.com, or @RobertMoran215 on Twitter.