A United States military installation in Japan has reportedly been subject to a series of massive explosions, with eyewitnesses claiming that a towering inferno and a series of loud blasts came from the base that houses American ammunition and petroleum products.

Early reports of the incident continue to indicate that the explosions occurred at the Sagami General Depot U.S. Army base, which is located roughly 25 miles southwest of Tokyo.

“Fire from the American military base has occurred,” a statement from the Sagamihara Fire Department said, according to the Japan Broadcasting Corporation (JBC).

An eyewitness told Japan’s NHK news: “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.”

NHK reports that about 580 people work at the military installation.

The Sagami General Depot is home to the U.S. Army’s 35th Combat Sustainment Support Battalion (CSSB), Defense Commissary Agency Central Distribution Center, Defense Logistics Agency for U.S. forces stationed in Japan. The base has been the subject of negotiations between U.S. and Japanese diplomats. In 2006, the Army agreed to eventually return 128 acres of the facility to Japanese control.

The initial blasts occurred shortly before 1:00 A.M. local time, according to eyewitnesses.

Photos and videos of what is believed to be the blaze continue to be posted on social media sites.

A Commander at the base told The Guardian: “There are no reports of injury, and base firefighters and first responders are currently fighting the resulting fire to prevent its spread to nearby buildings.”

The Pentagon said on Sunday afternoon that it was aware of the reports but could not confirm that the explosion happened at the military installation.

“We’re aware of the report, but we don’t have confirmation that the explosion occurred on the base,” Pentagon spokesman U.S. Navy Commander Bill Urban told reporters.

In April, a series of explosions could be heard outside the base, leading Japanese authorities to believe that “left-wing” radicals were behind the blasts.

This story is developing and will be updated as more information becomes available.