Public broadcaster NHK's live footage showed the blaze burning across a wooded hillside in the western Hiroshima region and smoke billowing into the air.

The fire follows the issuing of a dry weather advisory in southern Hiroshima after a long period without rain, with residents urged to take care when handling fire.

The forest is flanked by a shooting range operated by the Maritime Self-Defense Forces (MSDF), which was conducting an "explosives training around 9:30 am (0030 GMT)" Friday, a spokesman told AFP.

"Gunpowder was being used for the drill," the official with the MSDF 1st Service School said, adding it "still remains under investigation" whether the explosives had caused the fire.

Around 60 firefighters and four helicopters had been mobilised to put out the blaze, which has engulfed at least two hectares (five acres) of forest, a local fire department told AFP.

No injuries have been reported, but authorities have urged roughly 150 residents at a nearby nursing home to start evacuating in case the fire spreads.

The forest is in Hiroshima's Etajima district, an island with a population of over 20,000 people.

Japan saw in 2024 its hottest year since records began in 1898, mirroring other nations as ever-rising greenhouse gas emissions fuel climate change.