Beijing, June 22 : At least 31 people were killed and seven others injured after an explosion caused by the leakage of a liquified gas tank ripped through a barbeque restaurant in China's Yinchuan city, authorities said Thursday. The blast occurred at around 8.40 p.m. on Wednesday night in the city's Xingqing district, reports Xinhua news agency. According to the authorities, of the seven injured persons, one remains in critical condition. On Thursday, President Xi Jinping called for all-out rescue and treatment of the injured and enhanced safety overhaul. Xi urged efforts to ascertain the cause of the accident as soon as possible and hold the relevant people accountable in accordance with the law. All regions and related departments should screen for and rectify all types of risks and hidden dangers, he noted. Under Xi's instruction, a work group composed of several central government organs has been sent to the scene to guide the rescue efforts. The cause of the accident is under investigation. /IANS