Four brothers were killed instantly along with more than 40 other zama zamas (illegal miners) in a suspected methane gas explosion 3km underground in a decommissioned Harmony Gold mine in Welkom, Free State.

The four brothers – 28-year-old twins and their siblings aged 24 and 22 lost their lives in the explosion.

The explosion was felt across the tiny mining town – the epicentre of South Africa’s gold mine basin.

The explosion was so big that it shook buildings, rattled windows.

Some residents said it made their furniture move while many paid no attention: it was just the zama zamas.

Dozens of illegal mine workers were instantly vaporised or burnt beyond recognition. Some of those whose bodies have been found so far were identified by name tags on their bodies under clear sticky tape – a practice zama zamas have adopted to aid identification in the event of accidents.

The four brothers had worked underground for an illegal gold mining syndicate for six months.

The brothers are from Johannesburg and it appears th make huge amounts of money.

A Zimbabwean was identified as William Dube. There’s nothing left of him. Everything was burnt -100% of him is gone.’

Free State provincial police commissioner Lieutenant-General Lebeoana Tsumane said since Monday they had been retrieving bodies from the shaft.

He said the recovery operation would continue for as long as there were still bodies underground.