Bombings in the centre of the ethnically-mixed city of Baquba, north of Baghdad, killed six people including four children on Tuesday, an army officer and a doctor said.
The attacks struck the homes of a Sunni anti-Qaeda militiaman and a formerly internally-displaced Shiite family, both of which are in a neighbourhood that was an insurgent stronghold during the worst of Iraq's sectarian bloodshed.
In the first bombing, militants detonated explosives at the home of Arkan Mohammed, a fighter in the Sahwa, Sunni tribal militias that sided with US forces against Al-Qaeda from late 2006, helping turn the tide of Iraq's insurgency.
Mohammed's wife and two of his sons, aged 10 and 13, were killed in the bombing, according to an Iraqi army lieutenant colonel and Doctor Ahmed Ibrahim of Baquba hospital.
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The fighter and another of his children were wounded.
Around 15 minutes later, a bomb went off at the home of a Shiite Muslim family who had been displaced from the Gatoun neighbourhood but recently returned, the lieutenant colonel said, speaking on condition of anonymity.
The mother and two children died, while the father Mehdi al-Timimi and two other children were wounded, the officer and Ibrahim said.
During the peak of Iraq's confessional violence in 2006 and 2007, Gatoun was a stronghold of Al-Qaeda fighters, but levels of unrest have significantly declined since.
Attacks remain common, however, particularly in Baquba, and 126 Iraqis died as a result of violence in April, according to official figures.