Thirty miners were killed and 77 injured in an explosion at Tonghua coal mine in Chongqing muncipality on Saturday, the South China Morning Post reported. The blast was apparently caused by officials who used too much explosive trying to expand the mine and neglected to evacuate miners before detonation. According to the Chongqing Daily, local police detained three men yesterday: Chen Youming , chief engineer of the state-owned Songzao Mining Bureau of Chongqing; Liu Qiang , a project manager of the construction firm affiliated with the bureau; and Yi Zheng , the director of the mine. The municipal arm of the State-owned Assets Supervision and Administration Commission (SASAC) also suspended from duty Liu Mingyuan , the deputy general manager of Songzao, and Peng Zhiqiang , the board director and general manager of the construction firm. The mine had been temporarily operating at double capacity.