Four trucks have been set alight on the N2 between Ermelo and Piet Retief in Mpumalanga.
It comes amid a recent spate of attacks on trucks.
According to the police the trucks were set alight around 5am on Wednesday morning.
The road has been closed and traffic is being diverted.
Police have confirmed that a passenger has sustained burn wounds.
Provincial police spokesperson Selvy Mohlala says the passenger was asleep in one of the trucks when the incident happened.
Mohlala says armed men approached the trucks and instructed the drivers to vacate the vehicles before setting them alight.
VIDEO: On Monday, five trucks were on the Waterval Boven N4 road in Mpumalanga:
Earlier, a truck has reportedly been set alight on the R59 Route in Gauteng.
Police Minister Bheki Cele and the South African Police Service (SAPS) management will brief the nation on Wednesday regarding the police’s response to acts of violence targeting freight trucks.
The South African Transport and Allied Workers’ Union (Satawu) says it will soon write to Cele to request that officers escort truck drivers.
Satawu Spokesperson Amanda Tshemese says the attacks are tantamount to economic sabotage.