A preliminary investigation has shown that flooding at a state-owned coal mine in North China's Shanxi province, may have started Sunday afternoon when workers dug into a network of old, water-filled shafts.

Of the 261 workers who were in the mine at the time of the flooding, one hundred and eight have been rescued safely. 153 still remain trapped. The mine is affiliated with a state-owned coal company, and covers about 180 square kilometers. It boasts more than 2.3 billion tons of coal reserves. The mine is currently under construction and is expected to produce 6 million tons of coal a year.