One person was killed by a car bomb, parked near a police station by suspected Islamist militants, in the Egyptian city of Alexandria early on Tuesday, security sources said.
The attack in Egypt's second-biggest city also wounded two people but there were no immediate details about the identity of the victims.
Security sources also said that unknown assailants had attacked a police station in western Alexandria with Molotov cocktails, setting it alight but causing no casualties.
On Sunday, about 25 people were killed in anti-government demonstrations on the anniversary of the 2011 uprising that ousted veteran autocrat Hosni Mubarak.
Activists accuse President Abdel Fattah al-Sisi of returning Egypt to authoritarian rule since the army removed the Muslim Brotherhood from power in 2013 and then mounted the biggest crackdown against Islamists in the country's history.
Sisi says he is committed to democracy in Egypt, a strategic U.S. ally with influence across the Arab world.
Islamist militants have killed hundreds of police and soldiers since then-army chief Sisi overthrew president Mohamed Mursi of the Muslim Brotherhood in 2013.
A law enacted during Sisi's rule severely restricted demonstrations, dramatically reducing unrest in Egypt.
However, signs of discontent emerged in the run-up to the anniversary of the 2011 uprising that raised hopes of greater freedoms in the most populous Arab country.