Six South African miners were killed when unknown attackers threw a petrol bomb at a bus the National Union of Mineworkers (NUM) said on Tuesday.
The bus was transporting them to the Modikwa platinum mine in north east South Africa.
The attack took place late on Monday night. Modikwa is operated by African Rainbow Minerals and Anglo American Platinum.
“Six workers were burned beyond recognition and the other workers had to escape through windows. We also do not know what is the motive of the attack,” Phillip Mankge, the NUM’s North East Regional Secretary, said in a statement.
Africa Rainbow Minerals and police could not immediately be reached for comment.
Several workers were also injured, Mankge said in the statement.
South Africa is the world’s top platinum producer and its platinum belt has been rocked by periodic bouts of violence and labour unrest in recent years with local communities demanding more jobs or more benefits from the industry.