An explosion at a chemical plant left three people dead and three others slightly injured on Friday in southwest China's Yunnan Province, Xinhua quoted local authority as confirming today. The blast occurred around 10:35 a.m. in Yunnan Dawei Coke Co. Ltd. in Qujing City when workers were maintaining facilities in the workshop. "The cover for a storage tank was blast off in the violent explosion," a witness said. Three workers were killed at scene and the injured were rushed to a local hospital. The cause of the blast is under investigation.