Hundreds of workers were still trapped 2.4 kilometres underground in a South African gold mine Thursday afternoon, a day after one of the most dramatic accidents in the country's mining history, according to dpa. Around 750 out of the 3,200 workers cut off from the mine surface Wednesday morning when a falling pipe damaged the main shaft were still waiting to be lifted to safety, the National Union of Mineworkers (NUM) said. The accident occurred at Harmony Gold's Elandsrand mine, near Carletonville, west of Johannesburg. The mine is operated by Harmony Gold, the world's fifth largest gold producer. Both NUM and Harmony Gold had earlier said they hoped the rescue operation would be completed by 17:00 pm but the effort looked set to continue at least until nightfall. Four workers had collapsed from exhaustion in the mine while waiting to be rescued and were receiving treatment in a mine hospital, a company doctor said. No other injuries were reported. The accident occurred at about 10.00 am (0800 GMT) Wednesday after a pipe broke off the top of the shaft cutting off power to the lift. "Nobody was injured, but there was extensive damage to the steel work and electrical feeder cords," Harmony Gold spokeswoman Amelia Soares said. A secondary shaft normally used for moving rocks swung into action in the early hours of Thursday ferrying the workers in small groups to the surface. By mid-afternoon around 2,450 exhausted and dusty workers had emerged into daylight at intervals of about 40 minutes. "The environment was okay, it was not too hot, but we had no water. They just brought some now this morning," said Pretty-Girl Cingo, a 25-year-old trainee miner, who had spent nearly 30 hours underground. It was dark underground, Cingo said, clutching the cling-wrapped ham sandwich and roast chicken leg given to each of the rescued workers by medic. Most of the miners were too tired to talk about their ordeal and trudged off to their living quarters for a shower and some rest. The accident has prompted sharp criticism of Harmony's mine safety policies from NUM and Minerals and Energy Minister Buyelwa Sonjica. The union has accused Harmony of negligence, claiming it failed to maintain a tunnel through which the workers could have been brought to safety much quicker via an adjacent mine. "When you have people underground working in a shaft there has to be an emergency exit, NUM representative Peter Bailey said. But the underground tunnel was flooded at the Elandsrand mine end, he said. The company rejected the criticism, saying the secondary shaft, which can only carry 75 people at a time and which took several hours to be "reconfigured" for the purpose, was adequate. Questioned by SAfm radio as to whether the shaft had been properly serviced, Lizelle du Toit, investor relations officer at Harmony Gold, said, "Yes, definitely." The accident comes amid growing complaints by unions over the poor safety record in the country's mines. Nearly 200 people die each year working underground, mostly from rockfalls. This year looks set to be even more deadly, with the toll already at 205, according to Bailey. Analysts say that falling gold yields have forced mining companies deeper underground in search of the precious metal, making it riskier for workers. Gold production in South Africa last year fell to 275 tonnes, its lowest level since 1922. The Elandsrand mine is 3,566 metres deep. A nearby mine is over 4 kilometres deep. NUM accuses the gold mining companies, who are enjoying record prices, of cutting corners to maximum their profit. Minerals and Energy Minister Buyelwa Sonjica on Thursday, during a visit of the site, announced that the mine was to be shut down for six weeks pending the repair of the shaft and a safety review. "This incident has highlighted the problem of infrastructure. No replacement of facilities has been made (at the Elandsrand mine) for over 30 years," she said. "We are going to tighten our regulations on mining," the minister vowed. If Harmony was found to have been negligent with regard to worker safety, the state would not hesitate to bring prosecutions, she said. "We look at this incident as a very serious wake-up call," an apparently contrite Patrice Motsepe, Chairman of Harmony Gold, told a news conference. South Africa is the world's largest producer of gold and platinum. Mining is one of the country's largest foreign exchange earners, along with tourism. The accident has dealt a further setback to Harmony, which last month cut its third-quarter profit forecasts, citing lower production and higher overhead costs.