Thirteen people have been found dead after a gas explosion in a Chinese coal mine, with 20 others still trapped.
Since the explosion at the privately-owned Jinshangou coal mine in the Chongqing region of China before noon on Monday, rescuers have been working to free the trapped miners. Two escaped earlier, Xinhua News Agency said.
"We are still working all-out to search for the 20 missing miners and will exert our utmost as long as there's still a ray of hope," Chongqing deputy mayor Ma Huaping said.
Xinhua said the 400 workers trying to rescue more miners were being hindered by debris blocking some of the mine's passageways.
Gas explosions inside mines are often caused when a flame or electrical spark ignites gas leaking from the coal seam. Ventilation systems are supposed to prevent gas from becoming trapped.
The State Administration of Work Safety ordered an investigation into the blast, adding that "those responsible must be strictly punished". Officials in Chongqing also ordered the temporary shutdown of coal mines producing less than 90,000 tons a year, Xinhua said.
China's mining industry has long been among the world's deadliest. The head of China's State Administration of Work Safety said earlier this year that struggling coal mines might be likely to overlook maintenance.
China is the world's largest producer and consumer of coal but has announced plans to shutter more than 1,000 outdated mines, as part of a broader plan to cut down on overproduction.