Four Harmony Gold employees were killed in an infrastructure maintenance-related incident at the Kusasalethu mine, near Carletonville, on May 7.
The families and relevant authorities were immediately informed and the affected area has been closed, pending an in-loco investigation.
“We are deeply saddened by this incident. At Harmony, we view our employees as part of the larger family.
"Our priority is now to support the families of the deceased and everyone affected by this tragedy," Harmony CEO Peter Steenkamp said in a May 9 media release.
Trade union the National Union of Mineworkers (NUM) said in a separate release that it was "deeply saddened" by the death of the four mine employees.
"The NUM is calling on relevant authorities to speedily investigate this unfortunate incident. We also call on the Department of Mineral Resources and Energy to enforce the laws and ensure that companies take full responsibilities for such incidents," it added.