A sound bomb was detonated near a police station in the northern city of Damietta on Friday, Al-Ahram Arabic news website reported.
No human casualties were reported, but several windows of nearby cars and houses were broken.
Police had defused improvised explosive devices in two different locations in the Nile Delta city on Thursday evening.
Egypt in recent months has seen a wave of militant attacks, including IEDs, bombs, and shootings. Most target police and army sites but civilians have also been killed and injured in the violence.
One person was killed and nine injured in four explosions in Giza, part of Greater Cairo, on Thursday.
Also on Thursday two bombs exploded at a bus depot in the city of Aga in the Nile Delta governorate of Dakahliya. There were no casualties.