Early Friday, a thundering blast at a military and industrial explosives plant reverberated across a tight-knit community in central Tennessee, razing an entire building on the plant’s sprawling campus and killing a still-unknown number of people.

At least 18 people remain missing after the massive explosion, which rattled homes miles away and rocketed debris for at least half a square mile. Officials have acknowledged fatalities but declined to give a number from what remained a chaotic scene long after the blast.

“We need our communities to come together and understand that we’ve lost a lot of people. This don’t only affect those families, it runs deeper … this could be people that you grew up with,” Humphreys County Sheriff Chris Davis said, noting one victim was a childhood friend of his.

The explosion occurred during an early shift at Accurate Energetic Systems, a manufacturer of military and demolition explosives that employs scores of local residents.

“Prayers are needed … our hearts are broken for the families and for the loved ones that lost their lives,” Wendall Stinson, the manufacturer’s CEO, said alongside officials Friday.

The blast triggered a series of smaller explosions, officials said, and the cause is still under investigation.

Here’s what we know as the investigation continues:

A screengrab from Google Maps sh