Four people died and another four were injured in an explosion at a pharmaceutical factory in Haikou City, capital of south China's Hainan Province on Tuesday, local authorities said. The blast occurred around 11 a.m. at Hainan Huigu Pharmaceutical Co., Ltd., according to the publicity department of the Haikou municipal committee of the Communist Party of China. An initial investigation found that the explosion was caused by alcohol-containing materials stored at the factory, Xinhua quoted the department as saying. The injured have been sent to hospital and are in stable condition, it said. A further investigation is ongoing.