A U.S. Air Force Osprey based in Japan crashed during a training mission Wednesday off of the country’s southern coast, killing at least one of the eight crew members, the Japanese coast guard said, Paralel.Az reports citing Associated Press.

The cause of the crash and the status of the seven others on board were not immediately known, Japanese coast guard spokesperson Kazuo Ogawa said.

The Osprey is a hybrid aircraft that takes off and lands like a helicopter, but during flight it can rotate its propellers forward and cruise much faster like an airplane.

Ogawa said the coast guard received an emergency call Wednesday afternoon from a fishing boat near the crash site off Yakushima, an island south of Kagoshima on the southern main island of Kyushu.

Coast guard aircraft and patrol boats found one male crew member, who was later pronounced dead by a doctor at a nearby port, Ogawa said. They also found gray debris believed to be from the aircraft and an empty inflatable life raft in an area about 1 kilometer (0.6 miles) off the eastern coast of Yakushima, he said.