SHENYANG - Four people died and 13 were injured in an explosion at a coal mine in northeast China's Liaoning Province late Sunday, provincial authorities said Monday.

The gas blast occurred about 1,000 meters underground at the Dayaogou Mine of Nanpiao Coal and Electricity Co., in Huludao City, at 8 p.m., said a statement from Liaoning's work safety bureau.

The injured were stable and being treated in local hospitals.

The state-owned mine has an annual production capacity of 550,000 tonnes.

Work safety officials are still investigating the cause of the blast.