JOHANNESBURG (AP) -- Eight gold miners in South Africa died after a magnitude-2.4 earthquake triggered an underground fire, and rescue teams operating deep below the surface were searching for a ninth missing miner, a mining company said Thursday.
Smoke and a rockfall had hampered searchers struggling to find any survivors after fire broke out 1.7 kilometers (one mile) underground at the Doornkop mine around 6 p.m. Tuesday, the Harmony company said in a statement. The mine is 30 kilometers (19 miles) west of Johannesburg.
On Wednesday morning, rescue teams located eight other miners who had sought refuge from the fire and brought all of them to the surface within several hours. On Thursday morning, Harmony announced the discovery of eight bodies.
The National Union of Mineworkers, a major labor group, said the rockfall had ruptured electrical cables, triggering the fire, and that water and ventilation pipes were also damaged. It called for an urgent investigation.
"Our members' lives must come first. The health and safety measures must be applied," said Livhuwani Mammburu, a union spokesman. "There is technology available to actively monitor seismicity underground. We wonder if Harmony has got that technology."
James Duncan, a Harmony spokesman, said the company has monitoring equipment.
"Seismicity is not an exact science," Duncan said. "The challenge is to stay abreast of current technology, make sure you have the best that is available and continue to strive for improvement."
South Africa has some of the deepest mines in the world, raising concern about the safety of workers who could be more vulnerable to tremors and other dangers. The Doornkop mine shaft extends about two kilometers (1.2 miles) below ground. Harmony's deepest gold mines go to twice that depth, Duncan said.
South Africa's ministry of mineral resources said its chief mine inspector visited the Doornkop mine on Wednesday.
Minister Susan Shabangu said this week -- just before learning of the fatal fire -- that miners' health and safety had improved significantly since a panel, formed after the end of white minority rule in 1994, found poor safety standards and inadequate enforcement of existing laws. The parliament will soon consider amendments that strengthen the country's mine health and safety laws, Shabangu said at an international mining conference in Cape Town.
More than 54,000 miners in South Africa have died in accidents since reporting began in 1904, and many more have died from exposure to hazardous dust, gas and fumes, the ministry says on its website. The Chamber of Mines, an industry group, said there were 112 deaths in South African mine operations in 2012, a 9 percent reduction over the previous year.
The mining industry in South Africa, a pillar of the economy, is struggling with increasing costs and labor unrest.
Workers have been on strike for two weeks in the country's platinum-mining sector, amid sporadic reports of clashes pitting protesters against mine security and police. In 2012, police shot and killed several dozen miners during labor unrest at a Lonmin platinum mine.
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