Local media say a teenage soldier has been arrested in connection with the attack.
Two soldiers have been killed and one seriously wounded in an attack by a fellow recruit at a military training range in central Japan.
The incident took place at a Japanese Self-Defence Forces facility in the city of Gifu on Wednesday.
“During a live-bullet exercise as part of new personnel training, one Self-Defence Forces candidate fired at three personnel,” the Ground Self-Defence Force (GSDF) said in a statement.
“The death of another person has been confirmed of the three who were shot at,” the GSDF added later, after earlier announcing one soldier had died and two had been injured.
Government spokesman Hirokazu Matsuno earlier said the attack happened at about 9.00am [00:00 GMT] and a suspect had been arrested without giving further details.
Public broadcaster NHK reported the suspect was a teenage soldier and had fired an automatic weapon.
A local police spokesman who declined to be identified told the AFP news agency the suspect was an 18-year-old candidate recruit who was detained by other soldiers on the spot.
The training range is administered by the region’s Camp Moriyama and is a covered facility of more than 65,000 square metres (about 700,000 sq ft).
Violent crime and shootings are extremely rare in Japan, where gun ownership is tightly regulated, but a number of high-profile recent incidents have raised concern.
In July 2022, former Prime Minister Shinzo Abe was shot on the campaign trail and later died. The man who attacked Abe did so over his alleged links to the Unification Church.
And in April, Prime Minister Fumio Kishida escaped unharmed after a man threw an explosive device towards him at a campaign event.
Security has been tightened in the wake of the incidents, with thousands of police deployed for May’s Group of Seven (G7) summit in Hiroshima.
Last month, police also arrested a man accused of killing four people, including two police officers, in a knife and gun attack in rural Nagano west of Tokyo.