The US Coast Guard is searching for five people who were on board the UH-60 Black Hawk helicopter that went down in the Pacific Ocean west of the Hawaiian island of Oahu.

Wheeler Army Airfield reported losing contact with the helicopter late Tuesday night, but the Coast Guard just acknowledged the search-and-rescue effort on Wednesday morning.

BREAKING: @uscoastguard & @USArmy searching for 5 missing Air Crewmen after after a Black Hawk helicopter went down near the island of #Oahupic.twitter.com/NrBEYfWnoK — Natasha Sweatte (@Natashasweatte) August 16, 2017

Debris was spotted about 2 miles (3 kilometers) west of Kaena Point, Oahu, around 11:30 pm local time on Tuesday (0930 GMT), according to AP.

Multiple ships and aircraft are taking part in the operation, which also involves the Army and the Honolulu Fire Department.

Two Black Hawks from the 25th Combat Aviation Brigade were on a routine training mission between Kaena Point and Dillingham Airfield, Lieutenant-Colonel Curtis Kellogg, public affairs officer for the 25th Infantry Division, told AP. The search began immediately after one of the crews lost visual and video contact with the other helicopter.

The crash comes ten days after a US Marine Corps MV-22 Osprey ‒ a tilt-rotor aircraft with a history of deadly crashes ‒ went down off the coast of Australia, killing three.