A 23-year-old man remains unaccounted for after a small plane crashed into Setauket Harbor Saturday.

Police say a Piper PA-28 carrying four people went down around 11 p.m.

Three of the plane's occupants were rescued and taken to Stony Brook Hospital, where they were treated and released. They were identified as Austricio Ramirez, 25, of the Bronx; Nelson Gomez, 36, of Queens; and Wady Perez, 25, also of Queens.

The fourth man aboard the plane remains missing. He has been identified as 23-year-old Queens resident Gerson Salmon-Negron.

Search crews and divers have been out repeatedly to find him, but so far have not had any luck. Authorities say search efforts will continue as conditions permit.

Relatives for Salmon-Negron were too distraught to speak with News 12 on camera, saying only that they hope he is found.

Investigators say the plane had left Fitchburg, Massachusetts, and was returning to Republic Airport in Farmingdale at the time of the incident.

Police say Ramirez, a student pilot, was at the controls when the plane began experiencing engine troubles. He turned the controls over to Gomez, the instructor pilot, who crash-landed the plane in Setauket Harbor.

George Klein, a neighbor who is himself a pilot, was among the first on the beach. He helped one of the plane's occupants out of the water.

Crews have recovered the plane and transported it to a dock in Port Jefferson. Investigators with the NTSB will work to determine what caused the crash.