A helicopter went down in the East River Sunday night, police said.
Police and firefighters have arrived at the scene and divers have entered the water, the New York City Police Department said on Twitter.
One person managed to get out while five others remained trapped inside the helicopter, according to sources. It's reportedly upside down in the river.
The FAA is investigating.
Mayor Bill de Blasio has been briefed on the incident, and divers with both the NYPD and FDNY are already searching the water, the mayor's spokesperson said.
The other three were taken to hospital in critical condition.
The New York City Fire Department tweeted that its members were with police at the location near 91st Street in Manhattan. At the time, the temperature was below 40 degrees Farenheit (4 degrees Celsius). The helicopter can be seen landing hard and tipping over.
Early reports indicate the helicopter was owned by Liberty Helicopter Tours and had been hired as a private charter for a photo shoot.
The National Transportation Safety Board will determine probable cause of the incident, the FAA said. Click here for updates.