A series of powerful explosions that rocked the northern Chinese city of Tianjin has left at least 44 people dead and wounded more than 500, the Xinhua state news agency reported Thursday. Authorities said 12 firefighters were among those killed in the two blasts, which happened late Wednesday in a warehouse storing unspecified hazardous goods. Firefighters were reportedly called to the warehouse at 10:50 p.m., with the explosion occurring around 40 minutes later, according to Xinhua. Chinese President Xi Jinping has vowed to launch a thorough investigation into the incident and urged “all-out efforts” to assist with vicitims and containing the fire, state media said. Firefighting and rescue efforts were temporarily halted Thursday due to concerns about what materials may be on site, according to a government statement.