Thousands of South African platinum mineworkers gathered on Saturday at Marikana to commemorate the second anniversary of the killing of 34 of their colleagues by police during a strike.
The workers were joined by community members on a rocky hill outside a Lonmin mine where the shooting took place.
The hill has become a monument to those killed in the massacre, which was captured on camera and beamed across the world in scenes reminiscent of apartheid-era police killings.
The striking workers had been demanding higher wages.
Several opposition political leaders attended Saturday's event, which Jacob Zuma described as "a day of reflection".
Mineworkers, some carrying banners reading "Remember the Victims of Marikana", some wearing T-shirts emblazoned with images of their slain colleagues, arrived in groups, chanting slogans.
"I am here to support the families of the workers who were killed on the koppie (hill)," said mineworker Eric Raadt.
"They were striking for a better life," he told AFP.
A few white crosses were planted near the hill at the Lonmin platinum mine north of Johannesburg to commemorate the massacre, the peak of violence lasting several days. Overall, the unrest is believed to have claimed more than 40 lives.
"This tragic day should be marked as a day of reflection and recommitment to peace and tolerance in the country," Zuma said in a statement.
"We need to recommit ourselves to ensuring that violence is never again used to solve problems of any kind in our country."
A judicial probe set up soon after the killings is still under way outside the capital Pretoria, having heard evidence from some of the country's top politicians.
Former police minister Nathi Mthethwa and now Deputy President Cyril Ramaphosa are among prominent figures who have appeared before the commission. Ramaphosa was at the time of the deadly strike a member of Lonmin's board of directors.
He became involved in the labour dispute after a senior Lonmin official urged him to use his "influence" to petition officials who had the "necessary resources at their disposal".
At a hearing Monday protesters shouted "Ramaphosa must resign!", forcing retired appeals court judge Ian Farlam, who is leading the inquiry, to briefly halt the proceedings.
Zameka Nungu, a widow of one of the deceased Lonmin mineworkers said Saturday's observance evoked "difficult memories".
"This day brings back memories of that day, when my husband was shot. It's very painful for me," she said.