Deadly blast hits US explosives factory, Many killed , 19 missing,

Aerial video from the scene in Bucksnort, south-west of Nashville, shows charred debris, smouldering vehicles and little remaining of the facilit

The explosion just before 08:00 local time was heard from miles away including in neighbouring counties

There is a huge emergency response at the scene, with one first responder telling the Associated Press they could not enter the site initially due to continuing detonations

The factory belongs to Accurate Energetic Systems, which specialises in the development, manufacture, handling, and storage of explosives/

With 19 people still unaccounted for and at least four having received hospital treatment, questions remain about the exact cause of the ammunitions plant explosion in Tennessee.

Speaking to reporters, Sheriff Chris Davis described the scene as "one of the most devastating" sites he'd ever seen, adding "there's nothing to describe, it's gone." He said there's a half square mile of debris from the explosion.

Families are grieving and and experiencing a "gauntlet of emotion", Davis said.

Davis has warned that investigations may take some time while multiple agencies involved work together to figure out what happened.

We heard earlier from Sheriff Chris Davis that the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) is one of the agencies on site "handling the scene”.

The ATF is a federal agency that regulates the US explosives industry and investigates crimes relating to explosives.

One of its jobs is to protect the public from unsafe or unsecure storage of explosive materials - which it does through regular inspections.

Companies are required by the ATF to have a licence if they want to import, manufacture or distribute explosive materials, and they need permits if they want to transport explosives.

According to its website, 9,309 bodies currently hold federal explosive licences - and they work across two main sectors: explosives and fireworks.

When a series of explosions went off at the weapons facility in McEwen, Tennessee, early on Friday morning, roughly 20 minutes from Monica Coblentz’s house, she was sat at her daughter's dining table.

"All of a sudden we just a heard a loud bang. We didn’t know if it was a gun or what," she tells me..

"Our dog started having a cow. We were afraid he had got hit by something or another," Coblentz says, adding that the dog was ultimately "fine".

Coblentz says she only found out what the noise was after later receiving a phone call from her son-in-law who is a volunteer member of the local rescue squad.A massive blast at a military explosives facility in Tennessee has left several dead and others missing, officials say .At least 19 people are unaccounted for following the explosion, according to a local affiliate of CBS News, with families waiting to hear news about their loved ones