"An improvised explosive was detonated in Al-Bitash district, injuring some pedestrians and damaging storefronts," the official, requesting anonymity, told The Anadolu Agency.
The official said that security forces blocked off the site and combed the surroundings.
He also said that bomb experts have defused another improvised bomb at a train station in Alexandria's Bakous district.
No group has yet claimed responsibility for the explosion, which comes hours after a series of simultaneous attacks in North Sinai reportedly killed 26 people and injured 47, according to security sources.
The "Welayet Sinai" militant group (formerly known as Ansar Beit al-Maqdis) has claimed responsibility for the attacks, of which the Egyptian government has yet to announce an official death toll.