Renewed violence in the Yemeni capital killed at least nine people on Thursday as street battles broke out between forces loyal to the regime and its opponents, medical and security officials said. The officials said six people died in central Sanaa when government forces shelled thousands gathered for a protest there with mortars and rocket propelled grenades. Snipers on rooftops also targeted the protesters at Change Square, the epicenter of Yemen's seven-month-old uprising, and adjacent streets. Three bystanders were killed by a mortar shell in Sanaa's northern Hassaba district, the officials also said. The district is home to several of the tribal chiefs who switched sides in March to join the opposition against the 33-year rule of President Ali Abdullah Saleh.