SHENYANG - Seven people were killed in a coal mining accident on Thursday in Jianchang county in northeast China's Liaoning province, local work safety authorities said.

At about Thursday noon, a roughly four-meter-long section of the mine's roof collapsed and buried seven miners in the privately owned Huatai Coal Mine, said a spokesman with the provincial safety supervision bureau.

The seven were taken to hospital but attempts to save their lives failed. Other miners who were working underground have been lifted out of the accident site with no serious injuries, the spokesman said.

The exact cause of the accident is still under investigation.

The mine's owner and responsible persons have been detained by police.