Four illegal miners have been shot dead at a gold mine run by Aurora Empowerment Systems in South Africa.

Aurora Empowerment Systems chairman Khulubuse Zuma said the men died in a shoot-out underground with guards at the Grootvlei mine in Springs, east of Johannesburg, on 9 August, reports Bloomberg.

Illegal miners use the network of tunnels that run for miles across the Witwatersrand, the world’s biggest gold field, to search for the metal.

The police is investigating the incident, reports Reuters.