A helicopter crashed over the Grand Canyon on Saturday night.
U.S. media reported 27-year-old Becky Dobson, 32-year-old Jason Hill and 30-year-old Stuart Hill died in the incident on Saturday afternoon (February 10).
Three further Britons - named by police as Ellie Milward, 29, Jonathan Udall, 32, and Jennifer Barham, 39 - were airlifted to University Medical Centre in Las Vegas, Nevada, along with pilot Scott Booth, 42.
The survivors of the crash were rescued during an operation that stretched into the early hours of Sunday morning, Bradley said.
In 1999, a helicopter operated by the company hit a tree, killing the pilot and seriously injuring an instructor.
In a statement, Bradley expressed his condolences to the family and friends of the crash victims.
Crews will work Sunday to retrieve the bodies of those who died in the crash, Bradley said, but weather conditions were hampering efforts.
First responders had difficulty reaching the four survivors due to windy, dark, and rugged conditions, Bradley said. The pilot, who survived the accident, suffered injuries to at least "one of his limbs", officials said.
Images have emerged showing flames and thick smoke rising from the boulder-strewn crash site.
A still from video footage of the crash's aftermath.
One picture appears to show a female survivor, wearing jeans and a white top, fleeing the scene as the fire rages behind her.
"I saw these two ladies run out of it, and then an explosion".
"The ladies were screaming ..."
FAA spokesman Allen Kenitzer earlier said the aircraft sustained considerable damage in the crash.
The National Transportation Safety Board and the Federal Aviation Administration are investigating.
The six passengers on a sightseeing helicopter that crashed during a tour of the Grand Canyon have been identified as British nationals.
On its website, Papillon calls itself "the world's largest aerial sightseeing company" and says it flies more than 600,000 people a year.
It also says it "abides by flight safety rules and regulations that substantially exceed the regulations required by the Federal Aviation Administration".
It's unclear what caused the crash.
The aircraft, which was operated by Papillon Grand Canyon Helicopters, fell down towards the western rim of the canyon, Sky News reported.
Brenda Halvorson, the CEO of Papillon Group, said: "It is extreme sadness we extend our heartfelt sympathy ot the families involved in this accident".
Six passengers and a pilot were on board the Papillion Grand Canyon Helicopters chopper when it crashed around 5:20 p.m. Saturday on the Hualapai Nation near Quartermaster Canyon.
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