The accident happened on Thursday morning on the R410 at Nonesi Pass in Komani, said provincial department of transport spokesperson Unathi Binqose.
The truck was carrying a full load of maize meal, he added.
“All occupants in the vehicle were declared blue [dead] on the scene by the EMS.”
The incident had blocked one lane before emergency services workers cleared the scene, said Binqose.
“It’s alleged that the truck had a brake failure before it lost control with its load. A case of culpable homicide would be opened at the Glen Grey police station for further investigations.”