China's state TV says at least 18 coal miners in the country's southwest have been killed by high levels of carbon monoxide.
One miner was found alive after the disaster on Friday (Saturday NZT) in the Diaoshidong mine in Chongqing, the report said. Rescuers are looking for five others.
China's coal mining industry used to be the world's deadliest, suffering more than 5000 fatalities a year.
Safety improved dramatically after authorities overhauled the industry starting about 15 years ago.