The Pave Hawk helicopter slammed into the coastal marshes of eastern England during a training mission. The military says the helicopter crashed at about 6 p.m. local time near Salthouse on the Norfolk coast.
The military worked Wednesday with local authorities to cordon off the site and hope to remove the bodies later in the day.
Bernard Bishop, a Norfolk Wildlife Trust warden, says conditions are difficult because the marsh flooded twice in recent weeks.
The aircraft was based at the nearby Royal Air Force station in Lakenheath.
The names of the crew will be released after families are notified.
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