Egyptian officials say twin bombings in Cairo have killed at least five people, a day before the sensitive third anniversary of the uprising that toppled longtime leader Hosni Mubarak.
In the first blast, authorities say a suicide car bomber killed at least four people and wounded nearly 50 others outside police headquarters downtown
A few hours later, another blast across the Nile River outside a Metro station in the neighborhood of Dokki killed one person and wounded several others.
The blasts occurred early Friday - the first day of the Egyptian weekend - when the streets were largely empty.
No one has claimed responsibility, though Islamist militants have been blamed for a number of attacks against security forces since the country's military ousted President Mohamed Morsi in July.
Television images of the first attack showed extensive damage to the police headquarters, with windows and walls blown out and a large crater in the street. The explosion also damaged the nearby Islamic Museum.
Egypt's first democratically elected president, Mr. Morsi came to power following the 2011 ouster of the country's longtime military-backed president, Hosni Mubarak.
Mr. Morsi's Muslim Brotherhood has denied government accusations it took part in any of the attacks. But it has continued to hold regular anti-government protests, some of which have turned violent.
The Brotherhood and Egypt's interim government have called for rival protests on Saturday, the third anniversary of the country's mass protest movement, raising fears of renewed clashes.
The Muslim Brotherhood was designated by the 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.