In Saturday's deadliest attack, gunmen broke into the house of an anti-terrorism police captain in the southern suburbs of Baghdad, killing the officer and his family in their sleep.
Police officials identified the dead as Captain Adnan Ibrahim, his wife and two children, aged eight and 10.
The attackers fled the scene, and killed another policeman who tried to stop them at a nearby checkpoint.
Meanwhile in the western Sunni province of Anbar, gunmen kidnapped eight policemen who were guarding a post on the main highway linking Iraq to both Jordan and Syria, according to two police officials.
Earlier in the day, security forces and gunmen clashed in the area after police tried to arrest a Sunni tribal sheik suspected of being behind the killing of three army intelligence soldiers stopped by gunmen near a protest site in the city of Ramadi last month.
Iraqi authorities had offered a bounty for the arrest or information leading to the arrest of the sheik, Khamis Abu Risha, and two other people they say were linked to the killings.
Elsewhere, in the predominantly Shiite city of Basra in southern Iraq, gunmen shot and killed a Sunni cleric, Assad Nassir, as he was leaving his house, police said.
Two Iraqi soldiers were also killed and two others wounded when a roadside bomb struck a group of soldiers arriving to inspect the scene of a blast that took place earlier in the northern city of Mosul.
A security official said a roadside bomb hit a police patrol in the northern suburbs of Baghdad, killing one policeman and wounding two others.