A car bomb attack has killed at least three people and injured dozens more close to the police headquarters in the centre of Cairo on Friday morning.<br /><br />Egyptian state television quoted witnesses as saying that gunmen opened fire after the blast.<br /><br />The explosion damaged the building and sent smoke rising over the city.<br /><br />Egypt has been rocked by political violence since Islamist President Mohamed Mursi was ousted by the military in July last year.
