A suicide bomb at the Cairo Security Directorate on Friday morning killed at least four people and injured 76.
Security sources said three of the dead were police officers.
A second bomb killed one person near a metro station in the Dokki section of Cairo. An ambulance driver said seven people have been injured.
A third bomb exploded near a police station, causing no casualties:
UPDATE: A third bomb goes off near Al Talibiyah police station in Cairo, gun fire heard. #Egypt"
— Hasan Sari (@HasanSari7) January 24, 2014
Late Friday afternoon, a fourth bomb exploded near a cinema in Giza, killing at least one person.
The explosion in the parking lot of the Security Directorate, in the Bab El-Khalk district, smashed the building’s windows and ripped off parts of its facade.
— Sharif Kouddous (@sharifkouddous) January 24, 2014
Crowds outside the security directorate calling for death of Brotherhood, one man said "we'll take their daughters,wives&return them naked"
— Bel Trew – بل ترو (@Beltrew) January 24, 2014
Extreme hostility against brotherhood at site of bohouth bomb. Chants"execute MB" "police army ppl one hand" pic.twitter.com/hO2rgvrEPv
— Heba Afify (@HebaAfify) January 24, 2014
An Interior Ministry spokesman said initial investigations showed that a car bomb might have been used.
The attacks come one day before the third anniversary of the rising that overthrew President Hosni Mubarak.