Angry supporters of Egypt's ousted president have stormed and torched two buildings housing the local government in Giza, the city next to Cairo that is home to the pyramids.
The attack came as the death toll from Wednesday's clashes between police and supporters of ex-president Mohammed Morsi rose to 525, according to health officials.
The Muslim Brotherhood put the death toll at a staggering 2,600 and the injured at around 10,000 - figures that are extremely high in light of TV footage.
An Associated Press reporter saw the buildings - a two-storey colonial style villa and a four-storey administrative building - set ablaze on Thursday.
The Giza government offices are on the Pyramids Road on the west bank of the River Nile. State TV blamed Morsi supporters for the fire. Its footage shows both structures burning with fire men evacuating employees from the larger building.
Tamarod, the youth movement that organised the mass rallies preceding Mr Morsi's ousting on July 3, called for the creation of popular committees to protect government and private property. The number of people injured in the clashes also rose, to 3,717.
The violence began when police moved to clear two sit-in camps in Cairo by supporters of Mr Morsi. The clashes there later spread to elsewhere in Cairo and a string of other cities. The health ministry said 202 of the dead were killed in the larger of the two camps, in Cairo's eastern Nasr City district.
The violence prompted the government to declare a nationwide, month-long state of emergency. A night-time curfew was imposed in Cairo, Alexandria on the Mediterranean coast, and 12 provinces where violence broke out.
The crackdown drew widespread condemnation from the Muslim world and the West, including the US, and Nobel Peace Prize winner Mohamed ElBaradei resigned as the interim vice president in protest - a blow to the new military-backed leadership's credibility.
"Today was a difficult day," interim Prime Minister Hazem el-Beblawi said in a televised address to the nation. While he said he regretted the bloodshed, he offered no apologies for moving against the supporters of Mr Morsi, saying they were given ample warnings to leave and he had tried foreign mediation efforts.