Gunmen shot dead a woman and her two daughters in Iraq Saturday and a roadside bomb killed a man and his son as nine died in other attacks, officials said.
Iraq is witnessing its deadliest violence since 2008, when it was emerging from a prolonged and bloody sectarian conflict between Sunni and Shiite Muslims.
The woman and her two adult daughters were killed in their home near Baquba, north of the Iraqi capital.
A Sahwa anti-Al-Qaeda militiaman said the women may have been informants for the security forces.
Gunmen also killed two brothers who were former Sahwa members near Baquba, where a bomb in the city killed one person and wounded five.
Sunni militants consider Sahwa militiamen, who joined forces with the United States from late 2006, helping to turn the tide of the war, to be traitors and frequently attack them.
In Tikrit, also north of Baghdad, a roadside bombing killed a man and his 11-year-old son as they walked in the city centre.
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Gunmen also killed a judge's two bodyguards in the northern province of Nineveh, and militants attacked a police checkpoint with automatic weapons, killing a policeman.
The judge was not with the guards when they were killed.
An explosion near a market in Baghdad and another on a main road killed three people and wounded 10.
Militants frequently plant bombs in public areas in an attempt to sow fear and reduce confidence in the government.
Security forces are also often targeted.
Violence has increased markedly this year, especially since an April 23 security operation at a Sunni anti-government protest site that sparked clashes in which dozens died.
Protests that erupted in Sunni-majority areas in late 2012 are ongoing amid widespread discontent among Sunnis who accuse the Shiite-led government of marginalising them.
Experts say Sunni anger is the main cause of the spike in violence this year.