TOKYO >> 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.

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.

U.S. Air Force Special Operations Command said in a statement that the CV-22B Osprey belonged to the 353rd Special Operations Wing assigned to Yokota Air Base. The crash occurred “while performing a routine training mission off the shore of Yakushima Island,” the command said.

While the U.S. Marine Corps flies most of the Ospreys based in Japan, the Air Force also has some deployed there.

Air Force Special Operations Command said search and rescue operations were underway. A U.S. official who spoke on the condition of anonymity because they were not authorized to discuss the crash could not provide further information on the crew’s condition pending notification of next of kin.

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

Ospreys have had a number of accidents in the past, including in Japan, where they are deployed at U.S. and Japanese military bases. In Okinawa, where about half of the 50,000 American troops are based, Gov. Denny Tamaki told reporters Wednesday that he would ask the U.S. military to suspend all Osprey flights in Japan.

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 person, identified only as male, 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.

The coast guard said it planned to continue searching through the night.

Japanese Chief Cabinet Secretary Hirokazu Matsuno said the Osprey disappeared from radar a few minutes before the coast guard received the emergency call. The aircraft requested an emergency landing at the Yakushima airport about five minutes before it was lost from radar, NHK public television and other news outlets reported.

NHK quoted a Yakushima resident as saying he saw the aircraft turned upside down, with fire coming from one of its engines, and then an explosion before it fell to the sea.

Prime Minister Fumio Kishida said he planned to seek a further explanation from the U.S. military, but he declined to say whether he would seek a temporary suspension of Osprey operations in Japan.

Ogawa said the aircraft had departed from the U.S. Marine Corps Air Station Iwakuni in Yamaguchi prefecture and crashed on its way to Kadena Air Base on Okinawa.

Japanese Vice Defense Minister Hiroyuki Miyazawa said it had attempted an emergency sea landing and quoted the U.S. military as saying its pilot “did everything possible until the last minute.”

Yokota Air Base is home to U.S. Forces Japan and the Fifth Air Force. Six CV-22 Ospreys have been deployed at Yokota, including the one that crashed.

In December 2016, a U.S. Marine Corps Osprey crashed off the Okinawa coast, injuring two of the five crew members and triggering complaints from local residents about the U.S. bases in Okinawa and the Osprey’s safety record.

A U.S. Marine Corps Osprey with 23 Marines aboard crashed on a northern Australian island in August, killing three Marines and critically injuring at least five others who were onboard during a multinational training exercise.