A string of attacks on Sunday left at least six people killed and seven injured in northern Iraq, police told the German Press Agency dpa.
The attacks came as elections workers continued counting the votes in the region, a week after parliamentary elections widely seen as a key test of Iraq's stability ahead of US combat troops' withdrawal by the end of the year.
In Sunday morning's worst attack, a roadside bomb killed four police officers and injured two others on patrol in the western Mosul district of al-Yarmuk, police said.
To the east of the city, in the Mosul neighbourhood of al-Mithaq, two civilians were fatally shot when they were caught in crossfire between police and gunmen, police told dpa.
Mosul is among Iraq's most ethnically and religiously diverse cities, and among the most dangerous. Despite successive security pushes that police say have netted hundreds of suspected insurgents in the past year, the city still suffers near-daily fatal attacks.
In the similarly diverse city of Kirkuk, some 200 kilometres to the south, five police officers were injured in separate attacks.
Three policemen were injured when a bomb attached to the bottom of their car exploded as they were on their way to work, police told dpa, while another officer was injured when a bomb in his car exploded in front of his house in central Kirkuk.
A fifth police officer was wounded when a group of men opened fire at him near a petrol station in the city, police told dpa.
Kirkuk has long been the subject of a rancorous dispute between Kurdish Iraqi politicians, many of whom hope to make the city the capital of a future independent state, and Iraqi Arab and Turkman politicians, who regard Kirkuk and its 10 billion barrels of proven oil reserves as integral parts of the country.