At least nine people were injured Wednesday in an explosion at a corn processing plant in northeast China's Heilongjiang Province, local authorities said. The explosion hit the Heilongjiang Longfeng Corn Development Co., Ltd. in Qinggang county at about 9:40 a.m. Wednesday, the county's publicity department said in a statement. The injured, including three in critical conditions, have been sent to hospitals in the cities of Daqing and Harbin. Fire fighters were working at the site to eradicate risks of more accidents. An investigation into the cause of the explosion is under way. The company, a leading agricultural products processing plant, has an annual corn processing capacity of over 1 million tonnes.