At least five trucks have been set alight on the N3 Toll Route near Mooi River in the vicinity of the toll plaza.
Three trucks are burning on the northbound section and another two trucks are on fire south of Mooi Plaza.
Reports of stone throwing and gunshots continue to be received.
Traffic is currently being diverted and the toll plaza is closed.
Law enforcement and emergency services are on the scene, but the situation remains tense, and road users are advised to avoid the area until calm has been restored.
Report problems or get emergency assistance on the N3 Toll Route between Cedara and Heidelberg by calling the 24/7 N3 Helpline on 0800 63 43 57 or follow @N3Route on Twitter for regular updates.