Supporters of ousted Egyptian President Mohammed Morsi are launching new protests, some setting fire to a government building in Cairo.
Egyptian state TV and witnesses say hundreds of Muslim Brotherhood supporters attacked government offices Thursday in Giza, torching the entrance. Separately, hundreds of marched through Alexandria demanding Mr. Morsi's return.
The renewed protests and violence follow Wednesday's violent crackdown by Egypt's military on Morsi supporters gathered in protest camps around Cairo and fighting in Alexandria and Suez.
Video being distributed by the Muslim Brotherhood showed hundreds of bodies wrapped in shrouds at Cairo's El Iman mosque. Egypt's health ministry says Wednesday's violence killed at least 525 people and wounded more than 3,700. The Muslim Brotherhood has put the death toll at more than 4,500.
Authorities had warned for days they would move against the protest camps.
The interior minister in the military-backed interim government, Mohamed Ibrahim, defended the actions of security forces, insisting they used minimum force against the camps and only fired tear gas.
Ibrahim blamed the Brotherhood for creating what he called a state of mayhem across the country by shooting at police, attacking government buildings and burning churches. But witnesses reported security forces firing live ammunition.