The spokesman for Egypt's Interior Ministry says a bomb went off next to a police institute in eastern Cairo, but caused no casualties.
The blast came the morning after a series of bombings targeted police across Cairo, leaving six dead and sparking fears of an intensification of violence following the ouster of Islamist President Mohammed Morsi in a military coup on July 3.
Gen. Hani Abdel-Latif told The Associated Press that the blast took place at 7 a.m. on Saturday in the busy district of Ein Shams, but damaged only the institute's walls.
The bombing came as Egypt marks the 3rd anniversary of the 2011 uprising that toppled longtime autocratic president Hosni Mubarak. Morsi supporters as well as military loyalists plan rival rallies.