Fifteen workers died after an explosion at a coal mine in northeast China, state media reported on Monday. The blast occurred on Sunday afternoon at a legally run mine in Qitaihe city, Heilongjiang province, according to the local news agency, which said the cause of the accident was still being investigated. Twenty-five workers were in the mine when the explosion happened, with 10 managing to escape. The bodies of the 15 killed were recovered on Monday, agency reported.