The US Mining Safety and Health Administration confirmed the collapse occurred at Patriot’s Camp 9 preparation plant, which washes coal from the Highland 9 mine.
MSHA said part of the top floor fell through to the bottom floor, coming dangerously close to a very serious incident.
Six people were allegedly inside the mine when the incident occurred.
Sounds of the structure cracking and popping alerted the workers to the imminent danger and gave them just enough time to evacuate.
The operator will bring in structural engineers and a construction company to repair the plant and ensure the rest of the structure is safe.
Patriot is yet to release an official statement about the incident.