In radio transmissions, the pilot issued a distress call of "Mayday" a few seconds later, he uses the words "engine failure".
The harnesses, which are different than traditional aircraft seat belts, are created to allow people to safely photograph from a helicopter with the doors open. The cause of the crash has not been officially determined.
Once it splashed into the East River, the helicopter flipped over and began sinking.
Cadigan moved to the city in 2017, taking a video journalism job with Business Insider after finishing his journalism degree at Southern Methodist University and an internship with WFAA-TV.
The New York Police Department now has possession of the helicopter.
On Monday, a law enforcement official identified the vicitms as Daniel Thompson, 34, and Tristan Hill, 29, both from New York; Trevor Cadigan and Brian McDaniel, both 26 from Dallas; and Carla Vallejos Blanco, 29, who was from Argentina.
A video posted online appeared to show the red helicopter descending into the water, its spinning blades chopping the river as it tipped over.
Before police confirmed the fatalities, a bystander who caught the crash on video posted a clip to Twitter, showing the helicopter plunging into the river before flipping over with its blades chopping at the water.
At least two of the passengers were dead when rescue divers got the scene, officials said. Emergency divers had to remove the passengers from tight harnesses while they were upside down. The Associated Press reported the aircraft was owned by Liberty Helicopters, a company that offers private charters and sightseeing tours.
The pilot freed himself and was rescued by a tugboat. The other hit the water shortly after take-off on a sightseeing flight, injuring six tourists and the pilot.
"The helicopter reportedly is inverted in the water".
As the helicopter was on a photo tour, Dinh-Zarr said the NTSB will be working with the NYPD to recover the personal cameras and other digital devices "to capture a digital portrait of the last moments of this flight".
One of the victims in the fatal East River chopper crash was a member of an Upper East Side church choir who had an angelic baritone voice, pals and parishioners said Monday. "We didn't see the helicopter anymore and then a yellow raft popped up and again we didn't see or hear anyone until we saw a person on top of the raft screaming and yelling for help and waving".
Police and divers braved the 50-foot-deep river, which was about 40 degrees Fahrenheit and moving at a speed of 4 miles per hour on Sunday night.