Three people died after supports collapsed on them at a coal mine in east China's Anhui Province, a spokesman with the Anhui Huainan Mining Group, the owner of the mine, said Thursday.

The accident happened at 7:52 p.m. Wednesday when miners were dismantling the supports that were no longer needed to hold up a tunnel at Lizuizi Coal Mine in Bagongshan District of Huainan City, said the spokesman.

The three miners died after the emergency treatment failed, he said.

The cause of the accident is under investigation, he said.

The state-run coal mine was founded in 1955. It produces 1.1 million tonnes of coal annually, with more than 3,000 employees.