Johannesburg - Metro police said on Friday that residents of the Slovo Park informal settlement near Lenasia, south of Johannesburg, protested after illegal electricity connections were cut off in the area.
They were demanding the re-connection of illegal electricity, said chief superintendent Wayne Minnaar.
"Residents are throwing stones at the vehicles on the N12."
He said traffic was diverted from the highway to the Golden Highway, Navana Drive and the Midway off-ramp.
"It is not safe for motorists to drive past the N12."