Initial investigation showed a blast that hit Shubra el Kheima national security building was carried out like another blast that hit the Cairo police department last year.

The pick-up truck laden with two tons of explosives was used in Thursday's blast.

Investigations showed the attack left a five-meter crater and the driver parked the car near the building, walked out of it and fled by a motorcycle that waited him in the scene.

Twenty-two people, including seven policemen and one police officer, were injured in the attack whick rocked the four-storey building of the national security branch of Shubra El Kheima, Qalyoubiya governorate, in the wee hours of Thursday.