BAGHDAD (AP) — A bomb attached to a minibus killed four people south of the capital Baghdad, an Iraqi official said Tuesday.

Maj. Muthana Khalid, spokesman of the Hilla provincial police, said the bombing was late Monday as the vehicle was travelling 50 kilometers (30 miles) south of the Iraqi capital. He said two policemen who were guarding the road were among the dead.

Also on Tuesday, gunmen killed two Justice Ministry employees in a drive-by shooting on the airport road in Baghdad, a police official said. Hours later, gunmen shot dead a police officer as he was walking near his house in Qayara, 40 miles (60 kilometers) south of the city of Mosul, said police.

Hospital medics confirmed the death toll. All officials spoke on condition of anonymity because they were not authorized to talk to media.

Violence has ebbed in Iraq, but attacks on security forces, officials and Shiite pilgrims are still common as insurgents attempt to undermine the Shiite-led government.