Recently-emerged movement calling itself "Hasam" claimed responsibility for an explosion on Friday that killed six personnel in Haram district, in Giza.
The explosion, which took place in an area with high security presence, injured three conscripts, an interior ministry statement said earlier.
The prosecutor general ordered an investigation to be opened into the incident.
The attack comes a few days after the interior ministry announced that it killed three Hasam Movement members in an exchange of fire in Assiut.
The ministry said in a statement at the time that the movement is an affiliate of the Muslim Brotherhood organisation.
In recent months, Hasam movement has stepped up attacks targeting security personnel and high profile figures.
The movement claimed responsibility for the death of a policeman in Beheira governorate, northwest of Cairo in October.
It also claimed responsibility for the assassination attempts of assistant prosecutor general late September and Egypt's former grand Mufti Ali Gomaa in August.
