CHANGSHA - Three people were trapped following a flooding underground a coal mine in central China's Hunan Province Thursday, local authorities said.

The accident occurred at about 10:50 am when 39 miners were working underground the Shanqiao Coal Mine in Hengyang county, the county government said in a statement.

Thirty-six mine workers managed to escape and the rest three remained trapped. Rescuers said they had heard sound of knocking underground the shaft, indicating the trapped workers might still be alive.

The rescue operation is still under way.