The company, Harmony Gold, initially said it contacted eight miners who had escaped to a refuge bay at a depth of about a mile from the mouth of the Doornkop mine, Eyewitness News 17 reported.
The company said it's believed a small earthquake in the area, magnitude 2.4, caused a rock fall, which cut a cable that sparked a fire underground. Eight workers escaped after the rock fall but nine miners remain unaccounted for and are presumed trapped in the mine, CNN reported.
The fire was reported Tuesday evening, Harmony Gold representative Charmaine Russell said.
"Rescue teams were then immediately dispatched, but access to the area has been hampered by smoke," Russell said.