Both entrances to Sunderland Ridge on the R55 in Centurion were blocked by protesters on Tuesday morning, causing severe traffic jams in the area.
It is unclear what has sparked the protests.
Police spokesperson Captain Kay Makhubela told News24 that he was on his way to the scene but could not provide any further details.
Vehicles set on fire during protest action in Centurion
Motorists took to Twitter, posting pictures and video footage of the gridlock and protesters.
This is a developing story.