The ministry says the early Wednesday blast also wounded 28 people. Earlier reports said 19 were wounded and that no one was killed.
The bombing in the northern city of Mansoura suggests a campaign of violence against Egyptian police is spreading.
Suspected Islamic militants have stepped up attacks against security forces in the Sinai Peninsula since the military ousted Islamist President Mohammed Morsi on July 3.
Authorities condemned the Mansoura bombing, calling it an act of terrorism. Morsi's Muslim Brotherhood, whose supporters have been involved in violent clashes with his opponents and security forces, also condemned the explosion.
The military coup followed protests by millions calling for Morsi's ouster.
|