A suicide bomber has driven his car into an Iraqi police patrol, killing six police officers, in the northern Iraqi city of Kirkuk.
The attack took place in a crowded commercial area, packed with people arriving for work.
The police said the number of dead was likely to rise. Eleven people were wounded, mainly civilians.
Kirkuk, an oil-rich city 250 km (155 miles) from Baghdad, is disputed between Sunni Arabs, Kurds and Turkmen.
Ethnic violence
Kurdish leaders want to incorporate Kirkuk into their semi-autonomous region, and the city has suffered ethnic violence since the US-led invasion of Iraq in 2003.
In the Arab parts of Kirkuk, al-Qaeda is still active.
Last night, a car bomb killed two people near a mosque in the south of the city.
Violence in Iraq has increased in recent weeks - though the US says the attacks are now less sophisticated.
And the BBC correspondent in Baghdad, Natalia Antelava, says there are fears that security will deteriorate further once US troops begin to pull out of Iraqi cities at the end of June.
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