At least four people were killed by carbon monoxide poisoning in a coal mine in Gansu Province, the local work safety watchdog said Sunday.

The accident took place at about 6 p.m. Saturday as five management officials of the Jinmiaogou Colliery under Kaifu Mining Co. felt ill while working underground in the shaft.

One was saved but the other four, including the head of the mine, were killed by the gas, the Production Safety Supervision Administration of Gansu told Xinhua.

Production of the mine, in an uninhabited region of Subei County in Jiuquan City, has been suspended ahead of the National Day celebrations slated for Oct. 1. However, the head of the mine led four subordinates into the shaft for safety checks after a fire triggered by a 4.8-magnitude earthquake in the area on Friday.

The coal mine, with all necessary production licenses, reported a production capacity of 150,000 tonnes a year.