HONOLULU (AP) — U.S. Coast Guard and military crews searched the ocean off Hawaii on Wednesday for five people aboard an Army helicopter that went down during a nighttime training exercise.

Officials at Wheeler Army Airfield near Honolulu reported losing communications around 10 p.m. Tuesday with the crew of a UH-60 Black Hawk, the Coast Guard said in a news release.

Responding teams spotted a debris field about 2 miles (3 kilometers) west of Kaena Point, Oahu, shortly before 11:30 p.m., the release said.

Honolulu Fire Department crews found parts of a fuselage and a helmet in the debris field, Capt. David Jenkins said.

A Coast Guard plane, two helicopters and several boats are being used in the search across an area with light winds and 2-foot seas.

Two Black Hawk crews were conducting training between Kaena Point and Oahu’s Dillingham Airfield northwest of Honolulu when communications were lost, officials said. Clouds and a few showers were in the area at the time.

Night training offshore is routine, said Lt. Col. Curtis Kellogg, public affairs officer for the Army’s 25th Infantry Division.

The search began immediately after one aircrew lost visual and video contact with the other helicopter, Kellogg 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 Army by Sikorsky Aircraft starting in the 1970s.

More than 3,000 Black Hawk aircraft are in service around the world, according to Sikorsky’s parent company Lockheed Martin. The U.S. Army owns 2,300 of them.

In April, one crew member was killed and two others were injured when an Army Black Hawk helicopter crashed onto a golf course in Maryland during a routine training flight.

In 2015, 11 crew members were killed when an Army Black Hawk helicopter crashed into the water off Eglin Air Force Base, Florida.