Rasool added that Iraqi Prime Minister Mohammed Shia al-Sudani had been briefed about the attack. An investigation was underway.
Two Iraqi security officials said nine were killed and clarified that the explosive device was a bomb. They said another three policemen were wounded in altercations with militants that broke out following the explosion, without elaborating.
The two officials spoke on condition of anonymity because they were not authorized to talk to the media.
On Wednesday, three Iraqi soldiers were killed when a bomb exploded during a security operation in the Tarmiyah district, north of Baghdad. Among those killed was the commander of the 59th Infantry Brigade.
No one claimed responsibility for that attack either, but remnants of the militant Islamic State group are active in the area and have claimed similar attacks in Iraq in the past.
IS was defeated and lost all territory it once controlled in Syria and Iraq, with its last stronghold in Syria falling to the U.S.-backed campaign in 2019. However, sleeper cells remain and have carried out attacks that have killed scores of Iraqis and Syrians.
In Iraq, the militants have successfully exploited security gaps across a patch of territory in the north because of an ongoing dispute between Baghdad and Irbil, the capital of the Kurdish-run semi-autonomous region of Iraq.
Rural areas of Kirkuk, Diyala, Ninevah and Salahaddin provinces in particular have been difficult to police, with Iraqi security forces spread thin and IS militants routinely terrorizing local residents. At times they have managed to overrun towns overnight due to the security gaps.
Associated Press writer Qassim Abdul-Zahra contributed to this report.
