Two army conscripts and four civilians were injured late on Sunday in a bomb blast in the Matariya district of Cairo, state-owned newspaper Al-Ahram reported.
The report said the bomb had been planted on a tram railway.
Two further bombs were also reportedly defused near the Al-Shorouk suburb, and two other bombs near Ramses Square on the same day.
Since the ouster of former president Mohammed Morsi, bomb attacks targeting infrastructure and security personnel have grown relatively frequent, sometimes causing severe damage or casualties.
Despite the attacks being blamed on Islamists, particularly the outlawed Muslim Brotherhood and its supporters, Egypt is also facing a major insurgency in North Sinai, headed by the “Islamic State”-affiliated group “State of Sinai”.