Chinese state media say 33 miners are trapped after a gas explosion ripped through the shaft in which they were working.
The Xinhua News Agency says the condition of those underground isn't known.
Citing local officials, it says the blast ripped through the mine in the sprawling western region of Chongqing shortly before noon Monday.
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China's mining industry has long been among the world's deadliest, although safety improvements and the closure of smaller, more dangerous mines have reduced the death toll in recent years.
China is the world's largest producer and consumer of coal but has announced plans to shutter more than 1,000 outdated mines. The head of China's State Administration of Work Safety said this year that struggling coal mines might be likely to overlook maintenance.