Bomb attacks have become increasingly frequent in Egypt, particularly in the restive Sinai Peninsula, since the army toppled Islamist president Mohamed Morsi in July 2013.
A policeman was killed and eight other people were wounded in Cairo on February 13 in an attack claimed by jihadists.
Earlier in the month at least 10 people were wounded when five bombs exploded close to police stations in the Mediterranean city of Alexandria.
Militants have killed scores of policemen and troops in bombings and shootings, mostly in the Sinai.
