The company did not detail the incident it said led to the inundation, only that the event occurred early September 16.

Buffalo’s emergency procedure was initiated and the mine was safely evacuated. No injuries were reported.

“Management is currently working to assess the extent and impact of the incident,” said Malcolm Campbell, chief executive officer of Buffalo. “The relevant government regulator, the South African Department of Mineral Resources, has been informed.”

Magdalena currently produces around 1 million tons of bituminous coal annually, or about 70% of the miner’s total annual production.

Buffalo Coal, formerly known as Forbes Coal, officially changed its name in July.