Water that had collected in an abandoned coal mine burst through into an adjacent work site, killing 12 miners, state media reported.
Twenty people had been working in a mine on Tuesday when water began pouring into it, the official Xinhua news agency said. Six escaped and two were rescued from the coal mine in Qianxi County in Guizhou Province.
An initial investigation found that water had built up in a neighboring mine, which was deserted. The miners became trapped when the water poured in, Xinhua said on Wednesday.
China's coal mines are the world's deadliest, with fatalities reported nearly every day in fires, explosions and floods despite government efforts to improve safety.