Police said the killings and abductions came when gunmen on January 26 attacked several checkpoints in the predominantly Sunni city.
The violence came as hundreds of mourners gathered for the funerals of seven demonstrators killed on January 25 when troops opened fire at stone-throwing demonstrators.
Iraq has seen weeks of demonstrations in predominantly Sunni areas against the Shi'ite-led government of Prime Minister Nuri al-Maliki.
In Baghdad on January 26, the parliament passed a motion that would limit Iraq's president, prime minister, and parliament speaker to two terms.
Maliki's allies dismissed the move as unconstitutional.