Eighteen people are missing after a blast at a military explosives manufacturing facility in Tennessee on Friday.
Humphreys County Sheriff Chris Davis said one person initially believed to be on site had been located at home. Four or five people were taken to a nearby hospital after the enormous explosion that levelled the factory.
“There’s nothing to describe, it’s gone,” he said.
The plant in Bucksnort, Tennessee – roughly 56 miles (90km) south west of Nashville – specialises in the development, manufacture, handling and storage of explosives. The cause of the blast remains unclear.
Aerial video from the scene showed charred debris, smouldering vehicles and little remaining of the facility, which is owned by Accurate Energetic Systems.
Sheriff Davis, who was visibly emotional during his first media briefing of the day, declined to say exactly how many people died.
But he noted that the plant had been up and running when the explosion happened and that secondary blasts forced first responders to keep their distance from the site.
Workers who had just started their day “now may be missing or deceased”.
“A lot of times, when I have these types of situations, I refer to them more than just a person…we’re missing 19 souls,” Davis said.
During a second briefing hours later, Davis confirmed that 19 people were still unaccounted for and that the explosion happened in a large building. It flung debris across a half square mile, he added.
“This was a massive enough explosion that I can tell you that folks in Waverly felt and heard this explosion,” he said, referring to a town about 15.5 miles (25km) north west of the facility.
Davis declined to answer whether he believed the explosion was accidental or intentional, saying that “we have to make the worst assumption in order to find the truth”.
Tennessee Governor Bill Lee in a social media post said his office was monitoring the ongoing situation, and referred to it as a “tragic incident”. State and local authorities were working with federal agencies to respond to the explosion.
Casey Stapp, director of media relations at TriStar Health in nearby Dickson, said two walk-in patients were treated for “minor injuries” from the explosion and have been released.
A third walk-in patient, Stapp said, is still being treated for minor injuries.
Local news media said patients were also being treated at other hospitals in the area and that residents who lived more than 20 miles away from the site could feel the explosion.
The factory, which sat on about 1300 acres of land, produced C-4, TNT and other high-grade military and commercial explosives and stored them there.
Accurate Energetics Systems has now ceased operations, the sheriff said. It is believed that the company employed about 75 people.
“They are focusing on their families, their employees,” Davis said.
The explosion took place on the border of Hickman and Humphreys Counties and prompted a massive response from local and federal agencies, including the Federal Bureau of Investigation and the Bureau of Alcohol, Tobacco, Firearms and Explosives.
The FBI and ATF secured the scene and declared it stable, Davis said.
Officers are expected to remain on the scene for several days, with a number of teams trying to figure out what happened, Davis said, promising a “slow and methodical” investigation.
Another blast took place at the same location in 2014. at a unit which was being operated by a company called Rio Ammunition.
Reports from the time said one man was killed and three were injured in that blast.
Mixing explosives and filling munitions is a “high-hazard, low-probability industry” when properly regulated, Ken Cross, former President of the Institute of Explosives Engineers, told the BBC.
“Competent staff are essential, and the majority of organisations provide relevant training and supervision for their explosives worker,” he added.
He also noted that, globally, there are reports of explosions in factories most weeks, but those are often in places that make fireworks or “that might be considered to have less than ideal explosives safety legislation and official oversight in place”.
