The accident happened about 11 p.m. Wednesday in Xiaoyi city in Shanxi Province, a major coal-producing region southwest of Beijing.
The actual number of casualties is difficult to verify, as the Chinese regime routinely suppresses or alters information.
Police have detained six people and others were being sought in connection with the incident, the report said.
A shortage of coal in China this year has driven up prices, prompting a surge in mining.
NTD contributed to this report