Rescue work after an explosion at a coal mine in central China is being hampered by dangerously high levels of gas.
Twenty miners are known to have been killed in the blast in Yuzhou, Henan province, and 17 are trapped underground.
More than 270 other miners escaped.
The Xinhua news agency reported the blast happened early on Saturday at the pit, which is owned by Pingyu Coal & Electric Co Ltd.
Mine engineer Du Bo told the agency the explosion unleashed more than 2500 tons of coal dust.
Xinhua said that 239 miners had managed to reach the surface but that 20 had been found dead and 17 were trapped.
The BBC reports it was not immediately clear how deep underground they are.
China's mining industry is the most dangerous in the world, with more than 2600 workers killed last year alone.
