Lt-Col Lungelo Dlamini said several people were arrested in connection with the fire.
“I cannot, at this stage, say how many people were arrested. I will release a statement with the figures later today [Thursday].”
Protesting residents set the building alight after 2pm. Dlamini was not sure whether the blaze had been extinguished.
“Fire engines have been deployed and police are stationed everywhere in the area.”
Dlamini said the situation in the area was still tense. A group of Bekkersdal residents marched to the nearby Simunye township earlier in the day. Police said the group was peaceful.