At least seven workers were injured after a gas tank explosion in east China\'s Shandong Province on Tuesday afternoon, the local government said. The blast occurred at 5:57 p.m. at Boxing Chengli Gas Supply Co., Ltd. in Boxing County, Binzhou City, according to a source with the county government. All the injured have been sent to a hospital for treatment, including two in serious condition. Firefighters were struggling to put out the blaze as of Tuesday evening. The cause of the explosion is unclear.