The helicopter crashed at approximately 3:15pm EDT (19:15 GMT) on Thursday.
It went down in the river between Newport, Jersey City and the lower Manhattan area in New York City.
The aircraft had taken off from the Downtown Manhattan Heliport at 2:59pm (18:59 GMT) and radar data showed it flew north along the Manhattan skyline and then back south towards the Statue of Liberty.
Video of the incident appeared to show the helicopter breaking apart midair and plunging into the Hudson River. The river is a busy shipping channel and as deep as 60 metres (200 feet) at points.
Witnesses reported seeing debris fall before the crash, and parts of the wreckage were later seen protruding from the water.