QUETTA: A coalmine explosion on Saturday killed at least 16 labourers and injured several others in southwest Pakistan, with over a dozen still trapped, officials said. Director of disaster management Attaullah Khan said methane gas had caused the explosion in a mine some 60 km (35 miles) east of Quetta city, capital of Baluchistan province. "We have retrieved 11 bodies," Khan said. He said over a dozen labourers were still trapped in the mine. Rescue work was in process, Chief Inspector of Mines Iftikhar Ahmad said. Accidents are frequent in the province"s mines and are mainly due to inadequate safety measures.