ROUGH CUT (NO REPORTER NARRATION)

British police said on Wednesday (January 8) that they would be working with the U.S. Air Force and others to find out why a U.S. military helicopter crashed on the coast of eastern England, killing all four crew on board.

Wreckage, including munitions, was spread over a wide area of the crash site in difficult terrain of the North Norfolk marshes.

A second helicopter, which had been taking part in the same training exercise as the one that crashed, landed at the site and was still there.

The helicopter, a Pave Hawk assigned to the 48th Fighter Wing based at RAF Lakenheath air base, was performing a low-level training mission along the Norfolk coast when it went down in marshland on Tuesday evening (January 7).

The cause of the crash, which occurred in a nature reserve near the village of Cley next the Sea, was not known. The area is about 130 miles (210 km) northeast of London.

Some local people heard the helicopter