Update: the N3 Toll Concession Company announced the partial-reopening of the N3 highway in both directions shortly before 11:00. Traffic was still severely backed up, but had started flowing again.
The SA Police service said public-order police (POP) had been deployed in the area and had cleared roads.
The Witness reported that police had used teargas and rubber bullets.
The company responsible for the N3 toll road between Durban and Johannesburg on Monday morning confirmed a "total road closure" due to protest action at Mooi River.
The protest started around dawn.
Protesters reportedly used burning tyres to block the national route, and there were some reports of rocks being thrown at cars.
The N3 sees the heaviest traffic of any long-distance toll road every Easter Monday as holidaymakers from Gauteng return from long weekend breaks in Durban and the surrounding KwaZulu-Natal coast on the same day.
This year a peak as high as 3,500 vehicles per hour was expected between 9AM and noon on Monday, with lesser peaks later in the day.
Police said surrounding roads were also closed.
The closure of the alternative R103 road meant the best way around the protest was via Greytown on the R33 and R74.
For those stuck close to the Mooi Toll Plaza, that would mean returning to Pietermaritzburg, some 60 kilometres back the way they had come, and rejoining the N3 after Colenso, a detour of around 50 kilometres in total – on roads not equipped for peak holiday traffic.
Photos and video from motorists on the road showed long queues – and little faith that they would be moving again any time soon.
The Ladysmith Herald reported that two trucks had been set on fire.
The Ladysmith Gazette reported that the blockade appeared to have been triggered by truck drivers who were protesting against trucking companies using foreign drivers.
A video showed a Spar delivery truck being deliberately disabled.
Other video clips showed trucks being looted and on fire.