The company which owns the prospecting rights to the abandoned mine in which at least 30 "illegal miners" were trapped says heavy rain may have been a trigger for the shaft's collapse.
Chinese-owned bullion producer Gold One owns the prospecting rights to the abandoned gold shaft, however was not currently working in it.
"The illegal miners have dug a tunnel right next to it to access the shaft and it has collapsed behind them," Gold One spokesman Grant Stuart said.
Emergency services in South Africa have been using a crane to shift a large concrete slab obstructing the shaft.
More top news
Brothers Andy and Jamie Murray have beaten Belgian pair David Goffin and Steve Darcis to take a 2-1 lead in the Davis Cup Final
Protesters gathered outside Downing Street to urge MPs to vote down plans to bomb the war-torn country
Strong winds, heavy rain and snow forecast across the UK