The bodies of an air crew killed when a US military helicopter crashed in Norfolk are unlikely to be recovered until tomorrow.
Air accident, RAF and US investigators have spent the day at the scene of the tragedy in which four people died when a helicopter came down on a marsh near Cley-next-the-Sea on the north Norfolk coast last night.
Norfolk Police confirmed paramedics were not needed to treat those inside the helicopter, suggesting they died on impact or soon after.
Debris is believed to have been strewn across an area the size of a football pitch.
The investigation into last night's Pave Hawk crash is being hampered by the fact that it was carrying munitions, meaning that bullets are scattered around the scene.
It was not clear whether all next of kin in the US had been informed and the deceased are not expected to be identified for at least 24 hours.
Speaking in nearby Salthouse this afternoon, Chief Superintendent Bob Scully said the Norfolk coroner, Jacqueline Lake, had given permission for the bodies to be removed from the site.
Mr Scully added: "You would be very much mistaken if you thought this would be a quick process.
"It all hinges on our ability to establish what happened and the removal of the casualties, who are sadly deceased, could disrupt the evidence so this must be done methodically step-by-step."
Mr Scully said the bodies could be recovered overnight or in the morning.
Commenting on speculation that a bird strike could have contributed to the crash, Mr Scully said: "It would be foolish to speculate. There are so many different scenarios and assumptions do not make for a good investigation."
Military investigators from the US and UK are expected to work together to establish exactly what happened once the police involvement was over, he added.
A 400-metre police cordon is expected to remain in place until Monday and the public have been asked to stay away.
Investigators are aware of how much ammunition was on board and are attempting to account for it all.
Bernard Bishop, a Norfolk Wildlife Trust warden for Cley, who lives opposite the marsh described the scene as a "nightmare".
He added: "It is just awful, terrible, one of the worst things I have ever seen.
"It's not something that anybody would want to witness and my heart goes out to the friends and families of those who died."
A second helicopter from RAF Lakenheath was also in the area at the time of the crash and set down on the marshes to try to assist. It remains alongside the crash scene.
Four members of crew were on-board this helicopter and were not injured, police said. They have been interviewed by officers.
Peter and Sue McKnespiey, who run Cookies crab shop in Salthouse, live near the crash site.
Mrs McKnespiey said: "We heard the helicopter come over very fast and very low.
"I don't know about engines but I am used to the sound of helicopters and this sounded very heavy and very unusual."
Mr Bishop said he had not heard any impact adding that the helicopter sounded "normal".
"The search and rescue crews quickly arrived and it was my job to escort them over the marsh," he added.
"The conditions are very difficult because the marsh has flooded twice in recent weeks so that's hampering their efforts to recover the bodies and make the helicopter safe.
"There's only one track in and out of the crash site, which is also restricting their movements. It's just awful. I've never known anything like and never seen so many people here at one time."
The HH-60G Pave Hawk helicopter was on a training mission from RAF Lakenheath - a base for the US Air Force - which lies on the Suffolk Norfolk border, around 50 miles from the crash site.
The 48th Air Wing of the US Air Force tweeted last night: "We can confirm that one of our HH-60G Pave Hawk helicopters was involved in an incident during a training mission outside Cley-next-the-Sea."
A statement from the 48th Fighter Wing of RAF Lakenheath later added: "US military officials are coordinating the recovery efforts with the UK police and the Ministry of Defence.
"The authorities have secured the crash site and established a cordon.
"The aircraft, assigned to the 48th Fighter Wing, was performing a low-level training mission along the coast when the crash occurred."
A derivative of the more famous Black Hawk helicopter, the Pave Hawk gets its name from the Pave acronym standing for Precision Avionics Vectoring Equipment.
They are used for combat search and rescue, mainly to recover downed aircrew or other isolated personnel in theatres of war.
They have a four-man crew and can carry up to 12 troops. Typically, training flights would replicate as closely as possible real missions which would mean weapons and ammunition would be carried.
Matthew Hancock, MP for West Suffolk which includes Lakenheath, said: "My heartfelt condolences are with the families and comrades of the airmen killed in the RAF Lakenheath helicopter crash.
"Lakenheath is a close-knit community, and I know that this tragic loss of life will be deeply felt.
"In Suffolk we never forget that the presence of the men and women of the 48th Fighter Wing helps guarantee Britain's security and shared freedoms. This crash reminds us of the bravery of our allies, in training and in war.
"I also wish to pay tribute to the emergency services, who had to confront both difficult terrain and the presence of live ammunition as they arrived at the scene of the crash."
Colonel Kyle Robinson, 48th Fighter Wing commander, said: "The loss of our Liberty Wing brethren is felt deeply across RAF Lakenheath.
"I can only imagine the hurt and sorrow felt by the family and friends of these airmen. You are in our hearts and minds.
"We're already feeling a great sense of support from across the air force and from our UK neighbours as we go through this difficult period.
"Thank you for keeping our airmen and their families in your thoughts and prayers."