A fire on a foreign-flagged cargo ship docked in an eastern Chinese port caused "heavy casualties" on Thursday, state media said, with President Xi Jinping calling for urgent search and rescue operations. "A foreign cargo ship of Beihai Shipbuilding Co., Ltd. in Qingdao, Shandong Province, caught fire during its port call for maintenance, causing heavy casualties," state news agency Xinhua said. Xinhua did not specify the number of casualties or the cause of the fire, said AFP. Xi "stressed the need to urgently search for missing persons... and strictly hold those responsible to account", it added. State media said that the fire broke out at around 11:15 am (0315 GMT). It was not clear whether it had already been extinguished. Premier Li Qiang also urged the search and rescue of "trapped" people, and for those injured to receive medical treatment, "and strictly prevent secondary disasters". Qingdao Beihai Shipbuilding is a major shipyard that operates as a subsidiary of the China State Shipbuilding Corporation. Xi warned that "all regions and relevant departments must draw profound lessons from this incident, thoroughly investigate and rectify all types of fire hazards".