Nine miners were killed and two others hospitalized in a coal mine accident in southwest China's Yunnan province Tuesday, local officials said Wednesday.

The miners were buried by a collapsing coal heap while clearing residue coal at a mine in Fuyuan county in the city of Qujing at 5:20 p.m. Tuesday. Nine of the miners died en route to the hospital, according to an official statement.

The two hospitalized miners are in stable condition, the statement said. Authorities are working to investigate the cause of the accident.

The incident marks the second deadly coal mining accident to occur in Qujing over the past two months. On Nov. 10, a gas explosion at a coal mine in Shizong county killed at least 35 miners. Authorities announced the end of rescue efforts after searching for eight missing miners for 10 days.