Gunmen wearing military-style uniforms broke into the house of a pro-government Sunni militiaman early on Wednesday and killed five members of his family, including three children, Iraqi officials said.
A police official said the gunmen shot the women and children as they were sleeping in their home in Abu Ghraib, a Sunni-dominated area that used to be a haven for al-Qaida in Iraq.
Seven other family members were wounded in the attack. The militiaman, Hameed al-Zobaie, was not in the house at the time of the attack, the police official said.
A medical official in a nearby hospital confirmed the casualties. The officials spoke on condition of anonymity because they were not authorized to release the information.
Police said the gunmen likely were targeting al-Zobaie, who is a member of the Iraqi Sahwa, or Awakening Councils. The group joined forces with U.S. troops at the height of the Iraq war to fight al-Qaida. Ever since then, it has been a target for Sunni insurgents who call its members traitors.
Insurgents have stepped up attacks in Iraq recently as the U.S. military prepares to withdraw from the country by the end of the year.
In an earlier attack, a car bomb exploded near a popular restaurant in a Shiite neighborhood in southwestern Baghdad late on Tuesday night, killing three people and wounding 10 others, police said Wednesday.