Twenty-three are confirmed dead and six others remain missing after a colliery gas explosion in northwest China's Shaanxi Province on Wednesday, rescue officials said on Friday.

As of 15 p.m. on Friday, rescuers had retrieved 23 bodies and were continuing to search for the other trapped miners.

The blast occurred at around 8 p.m. on Wednesday in a shaft at the Yaotou mine in Chengcheng County. Only seven of the 36 workers in the pit managed to escape, said a spokesman with the provincial government.

Rescue work began shortly after the accident, which was reported to the State Administration of Work Safety the same night, said the spokesman.

Yaotou mine is state-owned and run by the local government. Its designed annual output is 330,000 tons.

A rescuer said the mine was closed for repairs on Oct. 3, when a pit was flooded. "Drainage and repair work was still going on when the explosion occurred on Wednesday," he said on condition of anonymity.

Wednesday was a gloomy day for China's coal mine industry with two more serious accidents.

A pit in the northern Shanxi Province, China's leading coal production base, was flooded at 6:30 a.m. Wednesday, trapping seven miners.

Another colliery flood, reported at 7:15 p.m. Wednesday in central China's Henan Province, has killed six miner and trapped 20 underground.

Rescue work is continuing Friday at these two small, licensed coal mines with annual production capacity under 300,000 tons.