At least 44 people were killed after a large explosion rocked the north-eastern Chinese city of Tianjin, a news report said Thursday, according to dpa. Sixty-six people were critically injured out of a total of 520 people in hospital after the blast and fireball in the port city, according to the official Xinhua news agency. A dozen firefighting crews responded to the warehouse fire late Wednesday, Xinhua said in an earlier report. The first blast occurred around 11:30 pm (1530 GMT), around 40 minutes after the first fire crew arrived. Twelve firefighters were among the dead, Xinhua reported Thursday. China's national fire department said on its official microblog account that a fire started at around 10:50 pm (1450 GMT) Wednesday in a Ruihai Logistics Company warehouse storing "dangerous chemicals" before the fatal blasts.