LONDON (CBS) - Wednesday morning authorities are working to retrieve the bodies of four American service members killed in a helicopter crash on England's coast. The U.S. military is working with British police to figure out what went wrong Tuesday night.
The U.S. military helicopter was based at a Royal Air Force station that is host to United States Air Force units and personnel, about 130 miles north of London.
Investigators are collecting evidence around the marshland where a Pave Hawk helicopter crashed, killing the four-member U.S. Air Force crew.
Norfolk Police Chief Superintendent Bob Scully said, "After 2:15 the actual crash site I would describe as an area of debris on difficult marsh area of football field."
U.S. officials say the helicopter was on a low-level training mission over England's east coast when it went down Tuesday. Investigators won't say if the crew gave a warning they were in trouble. Scully said, "We're not speculating on what exactly occurred, all we received is that aircraft has crashed."
Last night, Police cordoned off a quarter mile area as they looked into what happened. Local police say at the time, a second helicopter from the same military base "set down" in the area to try to help the crew.
Local residents Pete and Sue McKnespiey think they saw one of the helicopters through their window, before the crash. Sue said, "It seemed like two headlights, I supposed that what it looked like to me, but it was going pretty fast."
The Pave Hawk is a modified version of the Black Hawk chopper. It is used in combat, as a search and rescue aircraft, as well as in humanitarian missions.
Police say the investigation into the cause of the crash could take several days because the chopper carried ammunition and bullets and went down in such a rural area.
Local police say after the British coroner office is finished with its investigation, they'll hand over responsibility for the crash site to UK and U.S. military air investigators. British military officials say the names of the American airmen killed in the crash will be released 24 hours after their families are notified.