A bomb exploded near the Egyptian foreign ministry in Cairo on Sunday.
Earlier reports from Egyptian state television had indicated a higher death toll, of four people.
Several more people were wounded by the explosion, which happened on a crowded street in the Boulaq Abu Eila neighbourhood.
Police have been scouring the area to check for more explosive devices.
No-one has claimed responsibility for carrying out the blast.
Armed groups have killed hundreds of policemen since Islamist president Mohamed Mursi was ousted from power last July.
Egyptian security officials say ties have been established between Islamic State – the militant organisation that controls parts of Iraq – and the Egypt-based group Ansar Bayt al-Maqdis.
