A U.S. Army depot southwest of Tokyo suffered several explosions and a large fire early Monday morning.

The flames broke out shortly after midnight at Sagamihara’s Sagami General Depot. A YouTube clip (see below) posted shortly afterward shows how the blasts set the skyline alight in the small town, which is located in Kanagawa Prefecture, about 40 kilometers southwest of Tokyo. (Just a few hours earlier, a small fireworks display had wrapped up a local festival in a nearby park.) According to the Japan Times, no injuries were announced.

The U.S. Army Japan released a statement detailing the substances—including compressed nitrogen, oxygen, and Freon—that were stored in the building. Reuters, meanwhile, cited the local fire department, which said the case of the explosion was unknown, but that there was no danger of the flames spreading because of the building’s relative isolation.

However, the public’s likely far greater concern was addressed by an U.S. Army spokesperson, who clarified to Reuters in an email: “The building that exploded was not a hazardous material storage facility. We are in the process of determining the contents of the building. The depot does not store ammunition or radiological material.”

Residents will no doubt be relieved by those details, especially considering recent news of another, far greater, explosion in the port city of Tianjin, China, which housed numerous toxic chemicals that and has left the public anxious and uncertain about their safety.

Nevertheless, images of rubble left in the blast’s wake have been quite unsettling. Those photos were released by American Army news outlet Stars and Stripes, which added that an investigation is ongoing.

While no foul play has been reported, some onlookers have made some pointed speculation about the blast. Two Twitter users in particular— @LauraWalkerKC and @northkoreafront—noted that a similar blast occurred at a U.S. Army base in Kanagawa this past April. Both of them tweeted a link to a Wall Street Journal article about the incident, and @northkoreafront even tweeted: “left-wing extremists have in past shelled US Kanagawa bases w/mortars (as recently as April 2015)” while conceding that, in this latest case in Sagamihara, there are “No details yet…”

—Kyle Mullin

Image: Screenshot from YouTube