Algerian police officials say four officers were killed and a fifth seriously injured in a roadside bomb attack east of the capital.

The attack took place Saturday as a police convoy was traveling in the restive Boumerdes region.

Police were escorting a civilian vehicle delivering official school examination forms. Saturday's victims were traveling in the same vehicle.

It's the third year in a row extremists in the Boumerdes have targeted convoys carrying the exams.

The North African nation experienced a bloody conflict between the government and armed Islamist groups in the 1990s. Sporadic attacks continue, generally targeting security officials.