Nineteen people were missing and possibly dead after a devastating explosion on Friday morning at a military explosives plant in Tennessee, officials said.

The explosion at Accurate Energetic Systems about 80 km west of Nashville occurred at 7:45 am local time, Humphreys County Sheriff Chris Davis told a press conference.

Davis said there were multiple fatalities but it was still too early to know precisely how many people had perished, saying it was still possible there were some survivors.

When asked to describe the building where the blast occurred, Davis said, "There's nothing to describe. It's gone."

Investigators from the FBI and the Bureau of Alcohol, Tobacco, Firearms and Explosives were at the scene working to determine the cause of the explosion, Davis said.

Aerial video on CNN showed what appeared to be the footprint of where a building once stood. In an adjacent parking lot, debris and what appeared to be ashes were scattered among a few parked vehicles.

Efforts to reach the company were not successful.

Accurate Energetic Systems develops, manufactures and stores explosives for "military, aerospace, and commercial demolition markets," according to the company's website. The 1,300-acre headquarters in Bucksnort, Tennessee, includes eight production buildings and a quality lab.

Hickman County Mayor Jim Bates told CNN the plant did not have a history of safety problems, although there was a small ammunition explosion there in 2014. That incident killed one person and injured three, according to The Tennessean newspaper. (Reuters)