An improvised explosive device (IED) exploded Tuesday near a branch of the defence ministry in Tayaran Street, Cairo, according to a resident in the area.
No casualties have been reported.
The IED reportedly exploded by the Department of Education near the defence ministry office in Nasr City.
The explosion is the fifth on Tuesday alone, following explosions in Cairo, Al-Arish, and Alexandria.
A number of bombs have also been dismantled on Tuesday before exploding. Two more bombs were dismantled in Cairo International Airport.
Small explosions have become a frequent occurrence since the ouster of Mohamed Morsi in July 2013. Usually the perpetrators are unidentified, while government sources often point to members of the outlawed Muslim Brotherhood.