Egyptian officials say a car bombing outside police headquarters in Cairo has killed at least three people, just a day before the sensitive third anniversary of the country's uprising.
State media reported at least 35 people were also wounded in the blast, which occurred in the mostly deserted downtown area of the Egyptian capital in the early morning hours of Friday, the first day of the Egyptian weekend.
Television images 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.
The explosion was heard in many areas throughout the capital, awaking startled residents, many of whom posted pictures on Twitter showing thick black smoke rising from the city skyline.
Islamist militants have been blamed for a number of attacks against Egyptian security forces since the country's military ousted President Mohamed Morsi in July.
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.