Johannesburg - Six people died and several were seriously injured when a petrol bomb was thrown at a bus transporting them to work at a mine outside Burgersfort, Limpopo police said on Tuesday.

"This gruesome incident took place at Driekop village outside Burgersfort when the faceless assailants pounced on a bus soon after it stopped at a pickup point at around 8pm on 2 April 2018, and petrol bombed it," said spokesman Motlafela Mojapelo.

"Police were alerted and found that the bus had already burned to ashes with six victims inside. Others escaped through windows with burn wounds and were taken to hospital for treatment."

The bus was transporting night shift workers.

Provincial police commissioner Lieutenant General Nneke Ledwaba condemned the attack and said a high level team of investigators had been assembled to hunt for the killers.