Workers were using more than two tons of dynamite to blast away rock in the coal mine when the accident occurred on Thursday evening, the official Xinhua News Agency said.

The accident also injured 46 people, including 12 who were in serious condition, the State Administration of Work Safety said on its Web site on Friday.

The victims of the accident in Shizuishan city in the Ningxia Hui Autonomous Region included six people working with dynamite and others who were passing the area in a vehicle and workers living in nearby sheds, Xinhua said, citing the mine's owner, Shenhua Ningxia Coal Mining Group Corp.

Police were questioning two people from Guangdong Hongda Blasting Co. Ltd., which was in charge of the blasting, Xinhua said.

The cause of the accident was under investigation and rescue work was continuing, it said.

China's coal mines are the world's deadliest, with numerous fires, floods and other disasters killing an average of 13 miners a day.

Many accidents occur in small mines with low safety standards or in mines operating illegally.

The government has promised for years to improve mine safety but energy-hungry China depends on coal for most of its power generation. -- AP