A worker injured in a flooded coal mine receives treatment at a hospital in Hegang, Northeast China's Heilongjiang province, May 2, 2012. [Photo/Xinhua]

Twenty-eight miners were working underground when the accident happened at about 7 am, at a shaft of the Junyuan No 2 Coal Mine located in the city of Hegang, said an official with the rescue headquarters of the accident.

So far, 10 have managed to escape on their own or with help, and rescuers are still searching for the trapped.

The cause of the accident is being investigated.