Six government officials, including Wang Zhuowen, deputy head of Zhuzhou's Youxian county in Hunan province, were removed from their posts after a deadly gas leak on Sunday killed 18 people, local authorities said on Monday.

Five of the officials were from the county's work safety watchdog and coal industry service center.

The leak occurred at around 11 am on Sunday at the Jilinqiao coal mine in Youxian county.

The authorities assigned responsibility to the six officials after a meeting with top officials in Zhuzhou, the city that has jurisdiction over Youxian.

According to a report by China Youth Daily, the gas leak was caused by emissions from an illegal metal recycling plant located in an abandoned mine tunnel adjacent to the Jilinqiao mine. Its shaft joined Jilinqiao, which allowed the poisonous gas to enter.

More than 100 rescuers in five teams from Hunan and neighboring Jiangxi province rescued 37 miners and sent them to hospital for evaluation and treatment.

Rescuers had to use oxygen tanks underground because there was little breathable air.

Cai Yongpeng, a rescuer, said his oxygen tank was so heavy that he was unable to carry both the tank and a miner he found. To get the man to a safety, Cai removed his tank and crept forward with the man on his back for 200 meters on a 50-degree slope.

He said rescuers had to work in shifts to go into the mine shaft. The rescue work was exhausting and required frequent rests.

A miner who asked not to be named said that after being informed of the gas leak, the mine manager asked workers to enter the mine to rescue their colleagues. Some members of the rescue team, including the manager, were among the deceased.

Investigators were in the process of testing substances in the poisonous gas. Police have detained an unspecified number of people pending the outcome of an investigation.

Feng Zhiwei and Xinhua contributed to this story.