An NYPD officer is facing murder and attempted murder charges after allegedly shooting two women in a Brooklyn apartment earlier this week. The New York Attorney General's office is also investigating the fatal shooting.

Authorities say that Yvonne Wu, 31, was off-duty when she opened fire on two women—her ex-girlfriend and her ex's new girlfriend—on Wednesday, just before 5 p.m. In a press conference after the shooting, Brooklyn South Assistant Chief Michael Kemper said that Wu was sitting outside the Bensonhurst apartment at 19th Avenue and 79th Street and told responding officers that she shot someone inside. Police then found a 24-year-old woman shot in the living room and a 23-year-old shot in the bedroom.

Both victims were taken to Maimonides Hospital, where the 24-year-old woman, identified as Jamie Liang, died. The 23-year-old woman, who has been described as Wu's ex, is recovering from her injuries.

"The whole incident is horrible," Kemper said. It's believed that Wu, a five-year veteran of the NYPD, used her service weapon during the incident.

According to the Daily News, Liang's friend said that Wu was stalking the new couple and that Liang wanted to report her to Internal Affairs, but Wu's ex-girlfriend allegedly refused. Sources told WCBS 2 that while Wu had stayed in touch with her ex, "their post-relationship communication was 'confrontational.'"

The Attorney General's Office Of Special Investigation, which looks into all fatal shootings by police officers, announced it has opened an investigation into Wu's actions.