Four people were killed and nine others were missing in a coal mine accident in China's Guizhou province, authorities said on Tuesday. The coal and gas explosion occurred around 9.10 p.m. on Monday in Zimujia coal mine in Panzhou City, Xinhua news agency reported.

The emergency rescue headquarters said the gas density in the mine had been lowered to less than 1 per cent from the peak of nearly 40 per cent. More than 60 rescuers were searching for the missing.