The gunmen escaped after the evening attack in an eastern neighbourhood of the main northern city of Mosul, police said.
Last week, a spate of bomb and mortar attacks targeted the homes and businesses of Christians in the capital Baghdad, killing six people and wounding 33 and drawing international condemnation.
Those attacks came less than two weeks after 44 Christian worshippers, two priests and seven security personnel died in the seizure of a Baghdad cathedral by Islamist gunmen and the ensuing shootout when it was stormed by troops.
On November 3, Al-Qaeda claimed responsibility for the hostage-taking at the Syrian Catholic cathedral and warned it would step up attacks on Christians.
In other violence on Monday, two car bombs in the town of Badoush just outside Mosul killed two people and wounded 16, police Major Khalid Jamal al-Din said.
“Two car bombs detonated today (Monday) at around 9:00 am (0600 GMT) in a residential compound for prison security guards in Badoush,” Jamal al-Din told AFP.
“Among the dead was Lieutenant Colonel Hussein Khalaf, the head of the prison’s emergency response team, and another civilian working in the prison.”
The explosions wounded 11 prison guards and five civilians, Jamal al-Din added.
On March 6, 2007, insurgents launched a major attack on the same jail and liberated 140 prisoners.
In the western town of Qaim on the Syrian border, two roadside bombs, one of them in a market, killed two people and wounded five, police Lieutenant Ali Shaker said.
And in Baghdad, two separate roadside bombs targeting police patrols in the centre and east of the capital killed a policeman and wounded seven people, three of them policemen, an interior ministry official said.
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