Chinese rescue workers recovered 18 bodies in a coal mine near the metropolis of Chongqing on Saturday.
One person could be saved, the Chinese state news agency Xinhua reports.
The miners ran into problems after a gas leak on Friday afternoon (local time).
Five miners are still being sought.
Rescue activities will continue on Saturday.
The government will also investigate the cause of the accident.
The incident happened in the coal mine of the Diaoshuidong coal mine, more than 1,900 kilometers southwest of the capital Beijing.
A similar incident at the mine killed three more people in 2013.
It is the second major mining accident in the region in two months.
In September, 16 more workers were killed by a gas leak in the Songzao coal mine.
China is one of the largest coal producers in the world.
The mines in the country are known to be very dangerous.
An estimated five thousand people die in their work every year.
Fifteen years ago, the government took additional measures to improve the sector, including stricter controls at companies.