The US military claimed one of its helicopters carrying Marines executed a hard landing near the North Korean border "while conducting routine flight operations".
A statement said the US Marine Corp. CH-53E Super Stallion had 21 people on board including five crew members, all of whom were taken to hospital.
Fifteen people have been released from hospital and six are in a stable condition.
"A comprehensive investigation will take place to determine the facts and circumstances surrounding this incident", the statement added.
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After a relatively mild and quiet night, an episode of rain for many of us tomorrow.
The 34-year-old from Coulsdon in Surrey died during the private party in Headley in the early hours of Monday, Surrey Police said.
The Home Office made the arrests at various restaurants across London on July 4.