Three people including an army general were killed and at least 28 wounded on Friday in militant attacks, some claimed by a group loyal to Islamic State, and clashes at Islamist protests around Egypt, security sources and health officials said.
Police were out in force at the demonstrations, organised by a hardline Salafi group calling for removal of the government of President Abdel Fattah al-Sisi, the ex-army chief who led the overthrow of elected Islamist president Mohamed Mursi in July 2013.
In Matariya, focal point for protests in Cairo, a civilian died before the gathering was dispersed, security sources said.
Hours before, an army brigadier general was killed and two soldiers wounded when gunmen in an unmarked car fired on a parking lot in nearby Gesr al-Suez, they said. One soldier later died.
The demonstrations were small. Reuters witnesses saw just 100 or 200 people in Matariya.
The interior ministry said it thwarted 10 planned bombings and arrested 224 people nationwide on Friday.
One officer was shot in Alexandria and a bomb injured four police in the Nile Delta town of Sharqiya. In Al-Arish, in largely lawless northern Sinai province, a bomb wounded six policemen, security sources said.
Violence also erupted in Beni Soueif, a southern town, and Kafr Sheikh in the Delta, they said.
Ansar Bayt al-Maqdis, Egypt's most active militant group, appeared to take responsibility for some attacks via what claims to be its official Twitter account.
Ansar has pledged loyalty to Islamic State, the ultra-hardline Sunni militants that captured territory in Iraq and Syria, and claimed responsibility for shooting the general, the Sinai bomb and another attack in Qalyubiyah province.
Reuters could not confirm the group's claims.
Since Mursi's ouster, Egypt has cracked down on his Muslim Brotherhood supporters, arresting thousands and sentencing hundreds to death in trials that drew international criticism.
Hundreds of Brotherhood supporters were killed in August 2013 when security forces cleared two protest camps in one of the bloodiest days in Egypt's modern history.
That crackdown and laws banning unsanctioned protests have dampened enthusiasm for the kind of mass rallies that helped remove President Hosni Mubarak in 2011 and Mursi last year.
Authorities have tried to curb radical preaching, replacing thousands of imams and controlling Friday sermons.
The Salafi Front designated Friday's protests the "Uprising of Islamist Youth", alienating secular critics of Sisi and limiting turnout.