A bomb has exploded near a police academy in Cairo.
Reports say at least one person was wounded.
The explosion occurred on the third anniversary of the uprising that toppled autocrat Hosni Mubarak.
It also came a day after a wave of bomb attacks targeting police killed six people and raised fears that an Islamic insurgency is gaining momentum.
An Al-Qaeda-inspired group based in the Sinai peninsula, Ansar Beit al-Maqdis, claimed responsibility for the January 24 bombings.
Islamist militants have stepped up attacks since the army toppled President Muhammed Morsi of the Muslim Brotherhood in July.
Hundreds of security forces have been killed.
Morsi's overthrow plunged Egypt into political turmoil which has hit investment and tourism hard.
More violence is expected on January 25, when rival political factions gather to mark the anniversary of Mubarak's downfall.
Based on reporting by Reuters and AP