* U.S. helicopter crashes in rural England
* All crew thought to have been killed, say police (Adds new Lakenheath and police statement, details)
LONDON, Jan 7 (Reuters) - Four crew on board a U.S. military helicopter were feared dead after their aircraft crashed in eastern England during a routine training operation on Tuesday, police and U.S. officials said.
The helicopter, assigned to the 48th Fighter Wing based at the nearby U.S. air base RAF Lakenheath, went down at about 1800 GMT on the north Norfolk coast, a rural area about 130 miles (209 km) northeast of London.
"We can confirm that one of our HH-60G Pave Hawk helicopters went down outside Cley during a low-level flying exercise," said a spokesman at the U.S. base.
"The conditions of the four crew members are unknown at this time."
There was no immediate information as to the cause of the crash.
Norfolk Police said in a statement there were believed to be four fatalities, and a 400 metre (quarter mile) area had been cordoned off while it was determined from the U.S. military what munitions the helicopter was carrying at the time.
"The helicopter has been confirmed as a USAF Pave Hawk HH60 helicopter from RAF Lakenheath and four occupants are thought to have died in the crash," the statement said. "Next of kin will be informed before further details on the victims are released."
The RAF Lakenheath website said the primary mission of the HH-60G Pave Hawk helicopter was "to conduct day or night operations into hostile environments to recover downed aircrew or other isolated personnel during war."
Lakenheath is also home to Europe's only F-15 fighter wing, and local media reported that F-15 planes had been flying over the crash site.
In 2001, two single-seat F-15Cs from Lakenheath crashed while on a low-flying training mission over Scotland, killing both pilots. (Reporting by Michael Holden; Editing by Mike Collett-White, Andrew Hay and Ken Wills)