U.S. Marines train at Hijyudai Maneuver Area in Oita prefecture, Japan, Aug. 1, 2024. (Kendrick Jackson/U.S. Marine Corps)

Two Japanese soldiers died this week of lightning strikes during training in western Japan, a spokesman said Thursday.

Sgt. Kento Tanitsu, 25, and Sgt. Ayu Kubota, 21, of the Western Army Tank Unit, were found in cardiac arrest at 12:06 a.m. Monday at the Japanese army’s Hijyudai Maneuver Area in Oita prefecture, the Ground Self-Defense Force spokesman said by phone.

Both were confirmed dead at 1:14 a.m. Monday; an autopsy determined they died from electrocution by lightning, he said.

“The death of our troops during training is extremely regrettable and we take this very seriously,” said tank unit commander Col. Motohiko Nakamura, according to the spokesman.

“I would like to once again express our heartfelt condolences to the family of the deceased,” Nakamura said.

The army will take all possible measures to prevent a recurrence, he said.

The two soldiers were playing the enemy role in infiltration training, the spokesman said. Their radio communication cut off with their last communication around 2 p.m. Sunday, he said.

The Self-Defense Force began search after they were unable to contact them by 10 p.m. Sunday, the spokesman said.

The area was under a lightning advisory at the time of the exercise, the spokesman said.

The Japan Meteorological Agency issued an advisory in Oita prefecture from early morning until around 9 p.m. Sunday, Kyodo News reported Thursday.

The army created a committee Sunday to investigate the incident, the spokesman said.

Some Japanese government officials are required to speak to the press on condition of anonymity.