The incident was reported Wednesday night just after 5 p.m. at a home in Bensonhurst, Brooklyn.
Police say the 31-year-old off-duty officer shot and killed 24-year-old Jamie Liang and shot a 23-year-old woman in what they believe was a classic love triangle.
The 23-year-old woman is expected to survive.
The off-duty officer, identified by police as Yvonne Wu, was inside the home before the two women arrived.
Police believe that the NYPD officer was having an "intimate relationship" with the 23-year-old woman.
Wu has been with the department for 5 and a half years. Sources tell Eyewitness News she was with the 72 Precinct.
The home where the incident happened belongs to the 23-year-old woman, but sources say Wu did not live with the 23-year-old woman.
The off-duty officer was taken into custody and transported to a hospital for an evaluation.
WATCH | Police give update on shooting:
It was not yet clear if the weapon used was Wu's service weapon.
Police said she was calm and very forthcoming when they arrived at the scene.
"I saw them put the woman in the car that they arrested and she seemed very calm, it was strange, it seemed like it was from a different scenario, you know she just seemed so peaceful, we weren't," said eyewitness Valerie Wares.
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