Officials say the killings, committed late on October 14 and early on October 15, were in apparent retaliation for the slaying of 17 Shi'ites whose decapitated bodies were found in Balad on October 13.
Meanwhile, police in the Iraqi oil city of Kirkuk says 10 people were killed on October 15 in five attacks.
In Mosul, northwest of Baghdad, a husband, wife, and two of their sons were killed early on October 15.
In the capital itself, an Interior Ministry official survived a roadside bomb attack that killed seven others.
In addition, U.S. statements say three U.S. soldiers and a marine were killed on October 14 in separate attacks.
In a new challenge to the Iraqi government, a Sunni militant network, the Mutayibeen Coalition, has announced it seeking to establishing an Islamic state in six Iraqi provinces, including Baghdad. The Mutayibeen Coalition includes Al-Qaeda in Iraq.
(compiled from agency reports)