Fifteen other vehicles were damaged in the violence. The construction company is building an oil storage facility but work at the site has been suspended.
Police spokesperson Lieutenant-Colonel André Traut said cases of public violence, housebreaking, theft, malicious damage to property and arson were being investigated.
“An apparent labour dispute at the WBHO construction site in Langebaan this morning (yesterday) turned violent when an estimated 1200 construction workers set vehicles and office infrastructure alight.
“SAPS members have been deployed at the site to quell the violence and maintain law and order.