The blast occurred at about 11 a.m. in the Xiangshui Coal Mine in Liupanshui City, Guizhou province, China's official Xinhua news agency reported.
Five of the 28 miners who were underground had been rescued and 18 were known to be dead by late afternoon.
The mine is part of the Guizhou Panjiang Group.
The cause of the explosion was under investigation.
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