NANNING - Four people died while attempting to illegally mine in a closed coal mine in South China's Guangxi Zhuang autonomous region on Thursday, local authorities said on Friday.

Four people were found dead in the mine around 8:40 pm Thursday. The mine is located in the village of Matian in Quanzhou county in the provincial capital of Guilin, according to a statement from Quanzhou's publicity department.

The precise cause of the villagers' deaths is not yet known. A further investigation is under way.