Eleven illegal miners were killed in an abandoned gold mine in Benoni near Johannesburg on Tuesday, South African authorities said.
The miners were believed to be killed by an underground explosion, according to the South African Police Service (SAPS).
Alerted by another group of illegal miners, police dispatched a rescue team to the scene to recover the bodies, but the rescue effort was hampered by toxic fumes in the mine shaft, Xinhua news agency reported.
A miner said that three other miners died in the same shaft last Sunday.
Benoni, where several abandoned gold mines are situated, is a hot bed for illegal mining.
In February, four suspected illegal miners were shot dead in a gold mine by rival counterparts in the area.