A young boy has been killed as supporters and opponents of ousted president Mohamed Morsi fought in Suez city, and police fired tear gas elsewhere to quell disturbances.
The confrontations came on Friday as pro-Morsi groups called for a week of anti-military demonstrations under the slogan "Massacre of the Century" - a reference to the August 14 crackdown by security forces on Islamists in Cairo's Rabaa al-Adawiya Square.
At least 600 people died in that operation and in clashes it sparked there and elsewhere in the country that day.
The boy, aged 10, was hit by a bullet in the head when pro-Morsi marchers clashed with opponents of the deposed Islamist leader after Friday prayers, security officials said.
Disturbances were also reported in some districts of Cairo and a few other towns.
Police fired teargas as pro- and anti-Morsi students pelted each other with rocks in the capital's Al-Azhar University, security officials.
On Thursday, Egypt's interim rulers gave police the power to enter university campuses to quell protests without seeking prior permission from the prosecutor general or university authorities as previously required.
On Friday, police also fired teargas to break up clashes in Rabaa al-Adawiya Square.