Two people found on Sunday following a deep-sea dive in search of a Japanese Self-Defense Forces helicopter have been confirmed dead, the Ground Self-Defense Force said, in the first official announcement of deaths resulting from the incident since the chopper lost contact in early April.

Earlier in the day, the GSDF said five bodies and part of the UH-60JA helicopter, which went missing with 10 personnel aboard off the southern prefecture of Okinawa, have been located.

The Japan Maritime Self-Defense Force submarine rescue ship Chihaya is pictured from Okinawa Prefecture's Ikema Island on April 16, 2023. (Kyodo)

The SDF are still working to recover the three other bodies that remain underwater as quickly as possible. A damaged part of the chopper has also been located and is expected to be retrieved by a private salvaging company.

The five bodies were found around 8:30 a.m. by divers on the ocean floor at a depth of about 106 meters. The search will continue for the other five personnel that remain missing.

The helicopter is believed to have gone down after it disappeared from radar shortly after taking off from a base on Miyako Island on April 6.

The discovery came following a deep-sea search made through saturation diving, a technique that allows divers to work at great depths for long periods.

Attempts to deploy the technique were halted Friday due to equipment flaws and paused again Saturday against a backdrop of bad weather.

Those aboard the helicopter included Lt. Gen. Yuichi Sakamoto, the 55-year-old commander of the GSDF's 8th Division based in Kumamoto Prefecture. Sakamoto assumed his position in March.

The bodies were discovered 6 kilometers north of Irabu Island, which is connected by a bridge to Miyako. The crash is believed to be an aviation accident although the exact cause remains unknown.

Neither of the two air traffic control centers in the area received a distress signal from the helicopter's emergency locator transmitter designed to automatically activate on impact.

The helicopter underwent a special inspection in late March after 50 flying hours and was taken for a one-hour flight to check its safety but no abnormalities were found at the time, according to the GSDF.

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