Harmony Gold said an underground mine explosion at its Phakisa mine in South Africa's Free State province has left three rescuers dead and two seriously injured.
The rescue team was investigating a suspected fire underground at the time of the accident, Harmony said.
All other employees working underground at that time have been reported as safe.
An investigation to determine the cause of the accident will be conducted once the area is declared safe.
This is the second accident to occur in Harmony's Phakisa mine in less than a week, following the death of a miner due to a rockfall on 19 June.