A high density of gas on Monday was hampering rescue efforts to locate nine trapped miners after a coal mine accident on Thursday left 34 dead in the southwest province of Yunnan. More than 60 rescuers were mobilized to install gas exhaust equipment at the Sizhuang Coal Mine in the county of Shizong as the risk of gas explosions has prevented rescuers reaching the trapped, said an official with the rescue headquarters at the coal mine. Efforts will continue to remove gas to ensure a safe condition for rescuers, said the official. The accident occurred at about 6 a.m. Thursday when a powerful gas outburst hit an underground platform and then another, trapping a total of 43 miners. By Monday, 34 bodies had been discovered while nine other miners remain missing. In northwest China\'s Gansu province, rescuers are rushing to pump water out after a coal flooding trapped seven at midnight Sunday in the county of Jingtai. It was not known whether the trapped, still to be located, were alive, said Fan Shijie, chief of the county\'s work safety supervisory management bureau. Fan said coal mine managers failed to work underground as required by national regulations, and further investigation is under way.