A security guard sustained critical injuries after protesting workers set fire to a building in Boksburg on Friday.
Several other people were injured and vehicles and property were set alight.
Netcare 911 spokesperson Shawn Herbst confirmed that an ambulance helicopter was dispatched on Friday afternoon to attend to the security guard who sustained serious burn wounds.
Herbst said Netcare 911 treated nine patients – five sustained moderate injuries and three sustained minor injuries.
Police spokesperson Captain Kay Makhubele confirmed the injuries and said the owner of the company and his wife were also assaulted, along with other employees.
He said four cars and two trucks were set alight. Makhubele said a case of malicious damage to property and assault had been opened.