A U.S. Osprey crashed near the island of Yakushima on Wednesday, killing at least one crew member, according to Japanese coast guard officials.
The Japanese Defense Ministry said the crash occurred around 2:50 p.m. local time and a large rescue operation is currently underway.
The Osprey was carrying eight service members, according to the U.S. Air Force Special Operations Command (AFSOC).
It’s unknown if the other service members are alive.
The aircraft was registered with Yokota Air Base in Tokyo. AFSOC said it was a CV-22B Osprey assigned to the 353rd Special Operations Wing.
Japanese news service NHK reported the Osprey rolled over mid-flight, describing a fire in one of the engines and an explosion before it plummeted into the water.
AFSOC said in the late afternoon on Wednesday that the cause of the mishap is unknown and emergency rescue operations are still underway.
U.S. Ospreys are a hybrid aircraft that take off and land like helicopters but can cruise much faster. They typically carry special operations troops during flights.
They have come under scrutiny after several crashes in the past decade. A 2016 crash in Japan’s Okinawa injured two people and prompted complaints from local residents.
In August, the U.S. Marines ordered a safety review after an Osprey crashed near Australia, killing three people.
And last year, the U.S. Air Force special operations branch grounded its entire fleet of the CV-22 Osprey after four incidents since 2017.
The U.S. military has identified past issues with the Osprey’s clutch that connects one of two engines to the propeller rotor and has slipped for unknown reasons, forcing emergency landings.
The Associated Press contributed.
— Updated at 4:27 p.m.