China has been hit by three mining tragedies - two of them ongoing - with safety issues raised in all of them.

Families of victims are devastated as:

A gas explosion at a coal mine in central Henan Province kills at least 12 people and leaves 32 missing;

Rescuers continue efforts to save 153 workers trapped in a flooded mine in northern Shanxi Province; and

Four miners die of carbon monoxide poisoning after an explosion in the south.

Wednesday's gas explosion in Henan destroyed the entrance of a mine owned by private Guomin Mining Co in Yichuan County, near the city of Luoyang.

The death toll had risen to 12 and about 32 people were believed trapped underground, local authorities said yesterday.

About 90 miners were working underground when the explosion occurred.

The blast killed eight miners underground and four on the surface. Officials said 50 miners were rescued, leaving about 32 missing.

The schedule of miners on duty at the time of the explosion was buried in the debris.

The mine's legal representative, Wang Guozheng, has disappeared.

Henan Governor Guo Gengmao, who is leading rescue efforts at the site, said: "Rescuers have determined the explosion occurred at the entrance to the pit after an underground gas outburst.

"There is still a chance those trapped underground survived the explosion."

About 100 rescuers are still racing to reach the trapped workers.

Guo ordered local police to find mine owner Wang Guozheng and freeze his assets.

Zhao Tiechui, head of the State Administration of Coal Mine Safety, has arrived at the site to coordinate the rescue.

"The pipe sending coal out of the mine was cut in half by the blast and a nearby 2-story building caved in," said a witness.

The families of the missing miners have gathered at the mine entrance.

Work safety authorities ordered the mine to suspend operations after a gas outburst on May 1, 2009, making production after that date illegal, a statement from the Henan Administration of Work Safety said.

Meanwhile, four people in the Guangxi Zhuang Autonomous Region were poisoned after self-made explosives detonated in an illegal mine shaft yesterday.

A rescuer was poisoned by the gas and taken to hospital, the Guangxi Public Security Department said.