Several people were killed or reported missing after a powerful explosion ripped through a military ammunition plant in the U.S. state of Tennessee on Friday, local authorities said.

Secondary explosions forced rescue teams to withdraw from the area, which was destroyed.

The blast occurred at an “Accurate Energetic Systems” facility near the town of Bucksnort, about 97 kilometers from Nashville.

Humphreys County Sheriff confirmed there were fatalities and missing persons, adding that investigations are underway to determine the cause of the explosion.