Bodies in cemetery
The attackers then dumped the bodies at the local cemetery, he added.
"It was an al-Qaeda group and they were wearing Iraqi army uniforms," Zoubai said.
Major-General Qassim Atta, a spokesman for the army's Baghdad operation, confirmed the toll, but gave a different account.
"Many cars were set ablaze and many shops heavily damaged due to the powerful explosion"
Major-General Torhan Abdul-Rahman, deputy police chief for Kirkuk
"The first indications we have is that 13 people were killed in a tribal conflict," he said.
Iraqi police and hospital sources said another deadly attack occurred in northern Kirkuk, where a car bomb exploded in a crowded market place, killing at least six people and wounding 10 others.
"Many cars were set ablaze and many shops heavily damaged due to the powerful explosion," said Major-General Torhan Abdul-Rahman, deputy police chief for the city.
The death toll is expected to rise, police said.
In a third attack, a bomb planted under a car parked near an Iraqi army checkpoint exploded, killing two soldiers and wounding six civilians in Baghdad's Mansour district, police said.
And a roadside bomb wounded three children on Sunday in a small town near Mosul, 390km north of Baghdad, according to police.
Violence has dipped sharply in Iraq over the past 18 months but attacks remain common in volatile areas such as Kirkuk.
Kirkuk is one of several flashpoints between Iraq's Arab-led government in Baghdad and minority Kurds that US officials fear could lead to renewed conflict in Iraq.
Kurds see the city and surrounding province, which lies over one of Iraq's longest producing oilfields, as their ancestral home and want it wrapped into their semi-autonomous enclave.
The city's Arab and Turkmen populations fiercely oppose those aims.
The tensions between both sides are often exploited by groups trying to reignite the sectarian warfare that almost tore Iraq apart.