South African police have opened fire on thousands of striking miners near Lonmin's Marikana platinum mine.
A Reuters cameraman said he saw at least seven bodies on the ground at the scene.
Lonmin is the world's third largest platinum producer.
The most recent shooting happened when police laying out barricades of barbed wire were outflanked by some of an estimated 3,000 miners gathered on a rocky outcrop near the mine, 60 miles (100km) northwest of Johannesburg.
Police officers said talks with leaders of the radical Association of Mineworkers and Construction Union (AMCU) had broken down, leaving no option but to disperse them by force.
"Today is unfortunately D-day," spokesman Dennis Adriao said.
In an earlier statement, Lonmin had said striking workers would be fired if they did not appear at their shifts this Friday.
"The striking (workers) remain armed and away from work," the statement read. "This is illegal."
The unrest at the Lonmin mine began on August 10, as some 3,000 workers walked off the job over pay. Those who tried to go to work on Saturday were attacked, management and the National Union of Mineworkers said.
On Sunday, the protest became deadly as a crowd killed two security guards by setting their car ablaze, authorities said. By Monday, angry mobs had killed two other workers and overpowered police, killing two officers, officials said. Officers opened fire that day, killing three others, police said.
Operations appeared to come to a standstill on Tuesday as workers stayed away from the mines, where 96% of all Lonmin's platinum production comes from.
Before the police advance, Joseph Mathunjwa, president of AMCU, which has been on a big recruitment push in South Africa's platinum mines, said there would be bloodshed if police moved in.
"We're going nowhere," he shouted through a loudhailer, to cheers from the crowd. "If need be, we're prepared to die here."
Ten people, including two policemen, had already died during nearly a week of clashes between rival groups of workers at the mine, the latest platinum plant to be hit by fallout from an eight-month union turf war in the world's largest producer of the precious metal.
While the walkout appeared to be about wages, the ensuing violence has been fuelled by the struggles between the dominant National Union of Mineworkers and the new Association of Mineworkers and Construction Union.
Disputes between the two unions escalated into violence earlier this year at another mine.
Both unions have blamed each other for the strife.
