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The explosion in Jilin province's Baishan city also left six mine workers injured, said Li Ruike, a spokesman for the provincial government.
He said he had no further details.
China's mines are notorious as being among the deadliest in the world because of lax regulation, corruption and inefficiency.
Last year, 2,433 people died in coal mine accidents in China, according to official statistics, or a rate of more than six workers per day.
Labour rights groups, however, say the actual death toll is likely much higher than official data indicate, partly due to under-reporting of accidents as mine bosses seek to limit their economic losses and avoid punishment.