The fire department of Sagamihara said the blasts occurred shortly before 1:00am Monday local time, national broadcaster NHK reported.
More than ten fire trucks were dispatched to the site of the fire, Sagami General Depot, which is a US facility used for the storage of fuel and munitions.
Japan’s Asahi newspaper reported that no general evacuation of nearby areas had been called.
“I was asleep, and at first thought it might have been the roar of thunder, but then there was a sequence of explosions for 10, maybe 15 minutes. A pillar of orange rose to the skies, and the air was filled with the smell of gunpowder,” one eyewitness told NHK.
The site, which has been underused in recent years, lies on prime real estate just 40km from the heart of Tokyo, and has been subject of negotiations, with the US planning to eventually return most of the territory, under the terms of a 2006 agreement.
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