The shooting happened just before 9 p.m. at a four-story building on 30th Drive near 23rd Street in Astoria.
The victims were two women, a man and a young boy about 5 years old, who were all found dead in a first-floor apartment.
Police have not yet released information on the gunman. Investigators say that a weapon has been recovered.
Detectives are investigating whether the deaths may have been a murder-suicide. "We don't lean either way but that is certainly something we will look to," said NYPD Chief of Detectives Dermot Shea.
The circumstances that led to the shooting are not yet known. It was not immediately clear if the victims were related.
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