TOPSHOTS An Egyptian policeman reacts as he walks through the site of a car bomb explosion that struck the Cairo police headquarters on January 24, 2014, killing at least four people in an early morning blast, police and health ministry officials said. The attack came a day before police were to deploy across the capital for the third anniversary of the uprising against Hosni Mubarak, with Islamists calling for mass protests against the new regime. AFP PHOTO / MAHMUD KHALED