UH-60 Blackhawk helicopter
A US Army UH-60 Blackhawk helicopter lands on the flight deck of the amphibious dock landing ship USS Harpers Ferry in the Arabian Gulf in a December 26, 2013 Navy/Mass Communication Specialist 3rd Class Mark El-Rayes/Handout via Reuters

A United States UH-60 Blackhawk helicopter has crashed while attempting to land on a vessel in the sea off the east coast of Japanese island Okinawa. The helicopter came down near US Army Camp Schwab. It is not yet known what caused the crash.

Conflicting reports have been received as to the number of injured personnel. Japanese Defense Ministry spokesman, Kentaro Kato, said five crew were in the aircraft, citing information from the US military. Seven people were injured in the crash and 17 crew members rescued, Kyodo state news agency reported.

A video of a Blackhawk helicopter bearing the markings "United States Army" broken into pieces on the deck of a ship surrounded by shipping containers has emerged. An Okinawa coast guard spokesman said later that calls from the US Camp Foster military police called off requests for assistance and that all personnel were accounted for, according to NBC news.

The island of Okinawa has a combined four US military bases and training areas, including Camp Schwab, Kadena Air Base, Futenema Air Base, and a Northern Training Area. Plans for a new US military base on the island have met with opposition from local officials.