CHENGDU:- Four people died and two others were injured in a coal mine gas explosion in southwest China's Sichuan Province, local authorities said on Thursday. The explosion occurred at about 9:30 a.m. Thursday at a coal mine owned by Shuangying Coal Co., Ltd. in the city of Neijiang, according to the provincial work safety authority. The injured are being treated in a local hospital. An investigation into the cause of the blast is under way.