A pilot who survived a New York City helicopter crash that killed five passengers told authorities he believed a passenger's bag might have hit an emergency fuel shutoff switch in the moments before the chopper went down, it has been reported.
A federal official who was briefed on the investigation spoke to The Associated Press on Monday. The National Transportation Safety Board (NTSB) said it would look at the switch, the chopper's flotation devices and even the photos on passengers' cameras to figure out what caused the crash Sunday in the East River.
NTSB member Bella Dinh-Zarr said the agency has not spoken to the pilot but hopes to do so.
"Mayday, mayday, mayday," pilot Richard Vance said in an emergency radio call as the Eurocopter AS350 tour helicopter foundered. "East River - engine failure."
The chopper flipped over and quickly sank, killing a Texas firefighter, an Argentine woman, a young video journalist, a former basketball team assistant and another person on what authorities said was a charter flight to take photos.
The helicopter's six emergency floats inflated, but Ms Dinh-Zarr said investigators would look at whether there were any problems with those devices or the harnesses available to passengers on a chopper that was legally allowed to fly with its doors open.
The NTSB and other agencies involved in the probe also hope to recover the passengers' cameras and electronics "to capture a digital portrait of the last moments of this flight", she said.
No-one answered an email on Monday to Mr Vance, a 33-year-old licensed commercial pilot for seven years who is also licensed as a flight instructor. A possible phone number for him in Danbury, Connecticut, was not working.
A floating crane slowly raised the submerged helicopter to the surface on Monday and towed it off to be examined, as Democratic US Senator Chuck Schumer said federal regulators should suspend flights by the helicopter's owner until the facts of the crash are known.
The owner, Liberty Helicopters, referred all inquiries to federal authorities. The Federal Aviation Administration said it was investigating whether the flight had met regulations.
Witnesses to Sunday's crash said the helicopter was flying noisily, then suddenly dropped and quickly submerged. A bystander's video showed the helicopter land hard and then capsize in water about 50ft deep.
Emergency divers had to get the passengers out of tight safety harnesses while they were upside down, fire department Commissioner Daniel Nigro said. Mr Vance freed himself.
The passengers who died included Dallas fire Officer Brian McDaniel, 26, and his high school friend Trevor Cadigan, 26, a journalist who hailed from Dallas but had recently moved to New York.
Mr McDaniel had been with the Dallas Fire-Rescue Department since May 2016.
"He decided he wanted to help people" and set out to do it, said Cole Collins, a childhood friend from Dallas. "He didn't care about being a flashy person or making a lot of money. He loved his family and friends and this city."
Mr McDaniel was visiting Mr Cadigan, who had recently finished an internship at the Business Insider news site.
"He was a smart, talented, and ambitious young journalist and producer who was well-liked and made a big contribution," Business Insider said in a statement.
Carla Vallejos Blanco, 29, was a tourist from Corrientes, Argentina, who had been in New York for a few days, said her country's consul in New York, Mateo Estreme.
Tristan Hill, 29 and engaged to be married, was most recently working at a sightseeing tour company but had previously been a basketball operations assistant with the Westchester Knicks, a Development League affiliate of the New York Knicks.
He "brightened every room he entered, with a contagious smile and an unparalleled enthusiasm for life," the team said in a statement.
The fifth victim was Daniel Thompson, 34, police said.