Rescuers were still searching on Monday night for 13 miners trapped underground after a gas blast killed four people in Northeast China.

A pit of the Jisheng Coal Mine in Baishan city of Jilin province was rocked by an explosion about 6 am.

Four miners were rescued, and emergency crews recovered the bodies of four dead miners.

Technicians were attempting to restore the ventilation system in the collapsed shaft to release any buildup of hazardous gases, such as carbon monoxide, said a spokesman for the State Administration of Work Safety who declined to give his name.

Authorities said 116 miners were working in the mine at the time of the blast. Ninety-five miners managed to escape.

The coal mine, which has an annual output of 210,000 metric tons, used to belong to the local government, but went bankrupt in 1995 and was sold to a private company in 2003. It resumed operations in 2008, local officials said.

More than 70 medical personnel and seven ambulances rushed to the scene.

The four rescued miners, who are in serious condition, are receiving medical treatment, sources with the State Administration of Work Safety told China Daily.

Primary investigations suggest that an outburst of highly concentrated gas caused the accident, said Wang Jinfu, an official with the city's publicity department.

The spokesman for the State Administration of Work Safety said that the Jilin provincial government has vowed to carry out safety checks at all coal mines in the province to prevent similar accidents.

Contact the writers at zhiyun@chinadaily.com.cn and liumingtai@chinadaily.com.cn