Eighteen people were missing and feared dead following an explosion at a munitions factory in rural Tennessee on Friday that obliterated the building and was felt for miles around.

The explosion at Accurate Energetic Systems about 60 miles (100 km) west of Nashville caused multiple fatalities but officials had yet to determine a death toll as of late Friday night.

Humphreys County Sheriff Chris Davis told a press conference the scene was “one of the most devastating situations that I’ve been on in my career,” and that it would take time to determine the cause.

“There’s not going to be a short explanation for that,” Davis said, adding that investigators from the FBI and the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) were at the scene.

When asked to describe the building where the blast occurred, Davis said, “There’s nothing to describe. It’s gone.”