South African police insisted they acted in self-defence in the shooting of 34 miners at a platinum plant as President Jacob Zuma vowed to uncover the cause of the killings in the deadliest protest since apartheid.
Police at the Marikana platinum mine run by Lonmin, the world's number three producer, said they opened fire when hundreds of workers stormed through teargas and rubber bullets trying to attack officers with gunfire, machetes and clubs.
But the nation recoiled from what local media quickly dubbed the "Marikana massacre", drawing comparisons to the deadliest apartheid atrocities, chiefly the 1960 Sharpeville massacre when white police killed 69 black protesters.
As the death toll mounted during the day, Zuma cut short a visit to a regional summit and flew to the mine, vowing to uncover the cause of the killings.
"It is clear there is something serious behind these happenings and that's why I have taken a decision to establish the commission (of inquiry) because we must get to the truth," Zuma said.
Police forensic experts work at the scene where 34 people died after police opened fire on striking mineworkers in Marikana on August 17. President Jacob Zuma announced a probe into the deaths of the miners, in the deadliest protest since apartheid.
"This is a shocking thing. We do not know where it comes from and we have to address it.
"This is unacceptable in our country, which is a country that everyone feels comfortable in. A country with a democracy that everyone envies."
The White House said Friday that the United States was "saddened" by the deaths and expressed confidence in a government probe.
"The American people are saddened at the tragic loss of life," White House deputy press secretary Josh Earnest told reporters.
"We note President Zuma's statement of shock and dismay and the remarks of other South African officials on these events and their efforts to resolve the situation without further bloodshed," Earnest said.
"We are confident that the South African government will investigate the facts around this case and, as always, we encourage all parties to work together to resolve the situation peacefully."
Analysts warned the shooting sends a negative message to investors in Africa's biggest economy, as it tries to fight widespread joblessness and poverty.
"The message is pure and simple: it's a negative message," said Iraj Abedian, CEO of Pan African Investments, who said it reflected badly on the company and unions but also political leaders.
"It does not augur well nor does it indicate a type of foresightedness to avoid a crisis of this nature and avoid preventable complexities in very tough times in global economic and financial conditions."
Police chief Riah Phiyega stood by her force, saying officers only used live ammunition after negotiation and crowd control tactics had failed.
"The militant group stormed toward the police, firing shots and wielding dangerous weapons," she said.
"Police retreated systematically and were forced to utilise maximum force to defend themselves."
So far 259 people have been arrested over the clash that left 34 dead and 78 injured, she said. Ten people, including two policemen, had died in earlier unrest at the mine.
Some workers at the mine were on a week-long wildcat strike demanding a tripling of their wages from the current 4,000 rand ($486, 400 euros) a month.
With little official information about the victims 24 hours after the incident, residents of a shantytown near the mine were fuming.
"Now I want to see my husband because his baby is crying," said Asakhe Mayaphi, 25, gesturing to the shacks behind her.
She last saw her husband Mzubanzi early Thursday, and did not know if he had been hurt or killed.
London-listed Lonmin said it would help the families identify and bury the dead. Many of the wounded were taken to a nearby hospital run by the mine.
It was the deadliest police action in South Africa since 1985, when more than 20 blacks were shot dead by apartheid police in Cape Town as they marked the 25th anniversary of Sharpeville.
This time the gunfire came from a mostly black police force, shooting at poor black miners who say their living conditions have hardly improved in the 18 years since apartheid yielded to all-race democracy.
South African police insisted Friday they only fired in self-defence in a clash with striking mineworkers in which 34 people died, the deadliest protest since the end of apartheid. Duration: 00:49
"I always thought that the Sharpeville massacre was history and it would never happen again. What we experienced yesterday under the democratic government was similar to Sharpeville," said Joseph Mathunjwa, head of the Association of Mineworkers and Construction Union (AMCU).
Before Thursday 10 people had already died at Marikana in attacks blamed on rivalry between the radical new AMCU and the powerful National Union of Mineworkers, a major ally of the ruling African National Congress.
The two unions condemned that violence, denied taking part in the killings and blamed each other for the troubles.
Zuma's handling of the unrest could prove pivotal as he tries to stamp out leadership challenges within the ANC, ahead of the elective conference in December where he will seek a second term as party boss.
The NUM is one of South Africa's most powerful unions, having produced several top ANC leaders, including Deputy President Kgalema Motlanthe -- seen as a potential challenger to Zuma.