At least two people were killed after a helicopter crashed in the East River in New York on Sunday.
Three passengers are in critical condition at the hospital after being pulled out of the water by rescuers, city police said.
The New York Fire Department said the pilot was released.
Authorities confirmed that they had transported six people who took part in a photo shoot before falling near Roosevelt Island.
The helicopter belonged to a tour group, but police officer James O'Neill told reporters it had been rented privately by the team of photographers.
The video posted on social media showed a red helicopter appearing to make a semi-controlled descent before landing with some force in the water. Then it started to roll over.
In a press conference, New York Commissioner Daniel Nigro called the incident a "great tragedy."
"We are told that the five people were all tied tightly to straps that had to be cut and removed."
"It took time for the divers to get these people out, they worked very fast, as fast as they could," he said, adding that they also had to work against currents and water temperatures. below 4C.
The Federal Aviation Administration said it was investigating the incident.
The National Transportation Safety Council will determine the cause, he added.