Five people are dead after inhaling poisonous gas while stealing coal from an abandoned mine in southwest China's Yunnan Province Sunday, local authorities said Monday.

Hu Liubao and Niu Jianzhi led Zhao Xiaoyun, Leng Zhenxian, Yang Xiaochang and Yang Taoxian in extracting coal from the mine in Fuyuan County, Qujing City, said the county's information office in a statement.

All except Niu went down the shaft at around 5 p.m. Sunday and were found dead. The poisonous gas had yet to be identified, it said.

Police have detained Niu and Yunnan Coal Mine Safety Supervision Bureau is investigating the accident.