THE BRONX - The National Transportation Safety Board (NTSB) is investigating what caused a helicopter to crash in the East River yesterday afternoon, killing one person.

The chopper went down with five people aboard after taking off from the 34th Street Heliport for a private tour.

Four people were rescued from the water, including the pilot.

Officials were able to recover the helicopter from the water mostly intact and transported it to Floyd Bennett Field in Brooklyn.

"We're fortunate in this situation that the aircraft is mostly intact," says NTSB investigator Mark Rosekind. "So we'll be looking at the wreckage. Also, the pilot survived, so he's another source of information really critical for us."

VIDEO: Chopper 12 footage of East River helicopter crash scene1 killed when helicopter crashes into East River