A bomb exploded outside a police building in Cairo on Saturday, one day after six people were killed in a series of attacks targeting security facilities in the Egyptian capital, dpa reported.
Saturday's explosion injured one person and damaged a wall of the building in the eastern Cairo district of Ain Shams, state television reported.
The broadcaster quoted witnesses saying that unidentified attackers had hurled the bomb from a motorbike.
Security forces have been the target of attacks since July, when the military deposed Islamist president Mohammad Morsi after protests against his one-year rule.
The military-backed government has blamed the violence on Morsi's Muslim Brotherhood and labelled it a terrorist group.
Saturday marks the third anniversary of the start of the popular uprising that forced out long-time former president Hosny Mubarak.
Morsi became Egypt's first democratically elected president in June 2012.
Supporters and opponents of the military have called for rival rallies on Saturday to mark the anniversary, raising fears of violence.