Police officers in South Africa opened fire on striking miners, killing 34 and wounding 78 on Aug. 16 as violence between the largest mining union in South Africa raged on against a radical upstart union demanding sharp increases in pay and faster action to improve the grim living and working standards for miners.

On Aug. 17, South Africa’s police commissioner defended the actions of officers in Marikana who opened fire on miners. The commissioner, Riah Phiyega, described a desperate struggle by the police to contain the machete-wielding crowd of thousands of angry miners who broke through two lines of defense, leaving officers with no choice but to open fire with live ammunition.

“The militant group stormed towards the police firing shots and wielding dangerous weapons,” Commissioner Phiyega said. Previous attempts by the 500-strong police force to repel them with rubber bullets, water cannons and stun grenades had failed, she said in an emotional news conference, the New York Times reported.

“This is no time for finger-pointing,” Commissioner Phiyega said. “It is a time for us to mourn the sad and black moment we experienced as a country.”

President Jacob Zuma cut short his trip to neighboring Mozambique for a regional summit to rush to the site of the bloody protest, some 60 miles northwest of Johannesburg. It was South Africa’s worst labor-related violence since 1994.

The shooting left a field strewed with bodies and a deepening fault line between the governing African National Congress and a nation that, 18 years after the end of apartheid, is increasingly impatient with deep poverty, rampant unemployment and yawning inequality.

The police retrieved six guns from the protesters, including one that had been taken from a police officer who was hacked to death by the workers earlier in the week, Commissioner Phiyega said, as well as many machetes, cudgels and spears.

The strike has pitted the country’s largest mine workers union, which is closely allied with the governing A.N.C., against a radical upstart union demanding sharp increases in pay and faster action to improve the grim living and working standards for miners.

The strike and the government’s iron-fisted response are emblematic of the frustration with the slow pace of transforming South Africa’s largely white-owned business establishment and the growing perception that the A.N.C. and its allies have become too cozy with big business. As a result, many people here, especially the young, have looked for more radical solutions.

Besides those killed on Thursday, 10 other people, including two police officers, had already died as a result of violence connected to the strike, which began on Aug. 10 when thousands of workers walked off the job, saying that their wages needed to be tripled.