Five crew members are missing after a US army helicopter crashed into the ocean off Hawaii during a night-time training exercise.
Officials at Wheeler Army Airfield near Honolulu reported losing communications with the crew of a UH-60 Black Hawk at 10pm local time on Tuesday (9am BST on Wednesday), the US coast guard said.
Rescuers later spotted a debris field about two miles west of Kaena Point, Oahu.
A plane, two helicopters and several boats are being used in the search across an area with light winds and 2ft seas.
Two Black Hawk crews were conducting training between Kaena Point and Oahu's Dillingham Airfield at the time communications were lost.
The search began immediately after one aircrew lost visual and video contact with the other helicopter, a spokesman said.
The two helicopters are elements of the 25th Combat Aviation Brigade.
The UH-60 Black Hawk is a four-bladed, twin-engine utility helicopter manufactured for the US army by Sikorsky Aircraft since the 1970s.
Kaena Point is north-west of Honolulu.