A blast has shaken the headquarters of the police Security Directorate in central Cairo Al Jazeera reported
At least two people were killed in the attack early on Friday, with another 47 injured. The AFP news agency said the explosion was caused by a car bomb and left a crater in the road.
The Reuters news agency reported gunfire after the explosion. State television quoted witnesses as saying gunmen opened fire on buildings after the blast.
Smoke was seen rising over the city centre and a large number of ambulances were seen on their way to the blast site.
Pictures on Twitter and state television showed the exteriors of buildings damaged by the blast. The blast destroyed a metal gate outside the multi-storey building and badly damaged its facade, an AFP correspondent said.
A correspondent for Al Jazeera said that a museum had also been damaged by the explosion.