Photo taken on Nov. 1, 2016 shows the entrance to a pit at Jinshangou Coal Mine in Yongchuan District of Chongqing, southwest China. Rescuers are working around the clock to search for 20 miners who have remained trapped in a colliery in Chongqing for nearly 24 hours following a gas explosion. Thirteen miners have been confirmed dead. (Xinhua/Tang Yi)