Authorities say gunmen broke into a house north of the Iraqi capital and killed the sleeping family inside before blowing up the property.
Police said Sunday's early morning strike appeared to target a bodyguard of the mayor of Tarmiyah, 30 miles (50 kilometers) north of Baghdad.
The pre-dawn attack happened a few miles (kilometers) away, in the Sunni Muslim-dominated village of Mishahda. Police said the bodyguard, and his wife, sister and two young daughters were killed.
A medic at a military hospital in Tarmiyah confirmed the casualties.
There was no immediate claim of responsibility but al-Qaida in Iraq frequently targets government and security officials.