The helicopter came down in the river at around 7.15pm south of 86th Street said the New York police department (NYPD).
All five passengers were killed as the helicopter became submerged, despite the best efforts of police and fire service divers. The pilot managed to escape.
Footage of the crash shows the helicopter make what appears to be a relatively controlled landing, albeit at force, on the water. However, it then quickly lists as it sinks.
Two of the passengers were pronounced at the scene. The other three later died in hospital.
The helicopter had been specially chartered for a photoshoot, said police.
Commissioner James O’Neill of the New York City police department said: “Shortly after 7pm, we received dozens of calls of a helicopter crash in the East river just south of 86th Street.
“Harbour units from the NYPD and the fire department immediately responded. Aviation and the Coastguard responded too. A private tug boat also assisted in the response.
“A search and rescue operation immediately began. There were a total of six people in the helicopter, including the pilot.
“The National Transportation Safety Board will be conducting an investigation into the crash. The helicopter is owned by Liberty Helicopter Tours and it was a private charter for a photoshoot.”
Commissioner Daniel Nigro of the New York City fire department added: “There were six people in the helicopter. The pilot freed himself. The other five did not. So police and fire divers entered the water and removed the other five.
“Three of them were removed in a critical condition. They were removed to the hospital. Two of them were pronounced dead at the scene.
“The pilot is okay, he was taken to the hospital to be checked out but he was able to get out.
“It took a while for the divers to get these people out. They worked very quickly, as fast as they could. That’s 50ft of water there. There was a 4mph current and temperatures were in the low 40s (approx 5C).
“It is a great tragedy.”
Liberty Helicopters, which describes itself as the “largest and most experienced helicopter sightseeing charter service in the north east”, said in a statement on its website: “We are focused on supporting the families affected by this tragic incident and on fully cooperating with the FAA [Federal Aviation Administration] and NTSB [National Transportation Safety Board] investigations.
“These agencies have asked us to respect the investigative process by referring all press inquiries to them for any further comment.”
Liberty has been operating since 1990, offering standard, special and chartered tours of the city’s main sights.
The FAA confirmed the helicopter, a Eurocopter AS350, “went down in the East River near Roosevelt Island” and overturned, adding the NTSB would investigate the cause of the crash.