A rock flies past an opposition supporter during rioting against pro-Mubarak demonstrators near Tahrir Square in Cairo February 3, 2011. Anti-government protesters and supporters of Mubarak clashed on Thursday near a central Cairo square in a re-run of overnight violence that killed six and wounded more than 800 people. REUTERS/Goran Tomasevic (EGYPT - Tags: POLITICS CIVIL UNREST)