BAGHDAD, (AP) – Gunmen broke into the home of a Kurdish policeman in the northern Iraqi city of Kirkuk while he was away early Sunday, killing his wife and three children as they slept, authorities said.

Omed Abdul-Hamid had already left for work when the gunmen burst into the house and sprayed the woman and children with bullets, police Brig. Gen. Sarhad Qadir said. The children were ages 3 through 10, he said.

The attackers did not steal anything, suggesting it was an insurgent attack, Qadir said.

The oil-rich city has been at the center of tension between Arabs and Kurds, who want to incorporate the city into their self-governed Kurdish region despite opposition from Arabs and the Turkomen ethnic minority.

U.S. commanders have warned that insurgents are trying to exploit the tension to stoke an Arab-Kurdish conflict, which they say poses a greater long-term threat to Iraq’s stability than the Sunni-Shiite conflict.

Elsewhere in the area, two separate morning police patrols were hit with roadside bombs in southern Kirkuk, wounding six policemen, police Brig. Gen. Khatab Omar said.