The Algerian state news agency says a roadside bomb has killed four people and wounded 19 east of the capital.
The bomb was triggered as a military convoy passed through the district of Boumerdes, 30 miles (45 kilometers) from Algiers. The agency says a bus carrying civilian passengers was traveling behind the convoy. There were conflicting reports as to whether the victims were military, civilian or both.
The area is known as a stronghold of the North African branch of the al Qaeda movement.
On Wednesday, in the same district, a bomb targeting a police convoy exploded, but no casualities were reported.