Just going into a neglected quarry or shaft is hazardous; imagine going into one that hasn't been tended for years, then using rock drills and explosives to chase the last bits of gold.
Here's a more detailed status report on rescue work from The Citizen in South Africa.
Authorities haven't been able to shut all the illegal mines down, since the zama zamas live underground for months at a time, often adjacent to legal mines and sometimes connected to them. Many of the zama zamas are illegal immigrants, barred from holding regular jobs; expenses are paid by syndicates up top.
For a dramatic angle, here's a trailer for Zama Zama, a thriller about illegal miners of the Witwatersrand: