A series of explosions rocked the Cairo area Friday, including a suicide car bombing that left at least five people dead.
Investigators say the car bombing took place near a security facility early Friday.
A few hours later, a second blast occurred near a Metro station across the Nile River. Investigators say one person was killed and several police officers wounded in that explosion.
The Interior Ministry says a third attack occurred in Giza, near a police station on the main road to the Pyramids, but there were no injuries.
A fourth bombing was reported near a movie theater in Cairo, and initial reports said one person was killed in that blast.
There were no immediate claims of responsibility for the explosions, though Islamist militants have been blamed for a number of attacks against security forces since the military ousted President Mohamed Morsi in July.
A spokesman for interim President Adly Mansour condemned the violence, saying "terrorist operations that seek to break the will of Egyptians" will only unify them.
Later Friday, supporters of Mr. Morsi's Muslim Brotherhood clashed with security forces during protests in several cities.
The unrest came on the eve of the third anniversary of the uprising against former President Hosni Mubarak. The Brotherhood and the government have called for rival protests on Saturday.
Mr. Morsi came to power as Egypt's first democratically elected president following the 2011 ouster of Mr. Mubarak.
His Muslim Brotherhood movement was designated by the interim government as a terrorist group following the September bombing of a security directorate in Mansoura, a town north of Cairo, in which 15 were killed.
The al-Qaida-linked Ansar Beit al-Maqdis group claimed responsibility for that bombing, and most of the other biggest attacks, saying they are revenge for the government's crackdown on Islamists.