Sixteen people are dead after a blast at a military explosives plant in Tennessee, leaving no survivors, authorities confirmed on Oct. 11.

The blast occurred at a facility operated by Accurate Energetic Systems in Hickman County on the morning of Oct. 10.

Search efforts have been underway ever since to find any survivors. Sheriff Chris Davis, of neighboring Humphreys County, said about 300 first responders joined the search efforts.

Members of the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF) also responded to the blast incident.

Speaking at a press conference on Oct. 11, Davis indicated that responders have concluded that 16 people had been at the facility at the time of the explosion, all of whom were killed.

“We have notified all 16 families of those people that we feel [were] involved in this situation, this tragedy,” Davis told reporters.

Earlier in the search effort, Davis had told members of the media that as many as 18 people were thought to be potentially lost in the factory explosion. He said authorities have since determined that two of those people were not at the facility after all.

The Humphreys County sheriff indicated that the search effort has been slow-going, due to the hazardous nature of the materials at the site of the blast. Accurate Energetic Systems advertises a variety of explosive products, including military munitions.

“While this investigation is still in this early stage, at this point, the cause of this explosion has not yet been determined, and we will not speculate,” said Tyra Cunningham, of the ATF’s Nashville Division. “What we can say is that every effort is being made to conduct a thorough, methodical, and science-based investigation to find the answers that led to this tragedy and the answers that this community deserves.”

The Oct. 10 blast was heard as far as 15 miles away and flung debris up to half a mile around the site.

Davis previously described the blast site as one of the worst scenes he’s ever witnessed.

In an Oct. 10 social media post, Tennessee Gov. Bill Lee announced that his office was monitoring the incident and that state agencies were working in conjunction with federal and local authorities at the scene.

“We ask Tennesseans to join us in prayer for the families impacted by this tragic incident,” Lee said.

Sens. Bill Haggerty (R-Tenn.) and Marsha Blackburn (R-Tenn.) have also offered messages of condolences in response to the blast.

“Our prayers are with those affected and the first responders on scene,” Haggerty said on Oct. 10.

“My heart breaks for all those lost in the tragic explosion that took place in Hickman County yesterday,” Blackburn said on Oct. 11. “Please join me in prayer for the families of these victims, and I will continue working with local authorities to address this situation.”

The Associated Press contributed to this report.