More than 12 people have been killed and 42 hurt by a suicide bomber who opened fire inside a Sunni Muslim mosque before detonating his explosives' vest.
Police said the attack on Friday was in Tal Afar, a town between the northern city of Mosul and the Syrian border.
The attacker reportedly walked into the mosque with an AK-47 rifle during prayers, detonating his explosives belt once he had run out of ammunition.
Abdul-Satar Hassan, a member of Iraq's largest Sunni political party and the imam of the mosque, was killed.
It was not immediately clear if the imam was the intended victim, although Sunni religious leaders have increasingly become targets in Iraq.
Sahir Jalal, 37, who was at the mosque, said the imam had just begun delivering the sermon when a tall man stood up.
"Then he took out a small rifle from under his jacket and started to shoot," he said.
While violence in Iraq has dropped, the area in and around Mosul is considered one of the last strongholds of the Sunni-backed forces opposed to the US-led military presence in the country and the scene of some recent deadly attacks.
Tal Afar, a mostly Turkoman city, is located along one of the major smuggling routes from Syria to Mosul and has gone through erratic cycles of stability and instability for years.
In a seperate attack on Friday, a suicide car bomber killed at least one Iraqi soldier at an army checkpoint just outside Mosul, police officials said. One policeman was killed and four others wounded in a similar attack the previous day.
While Iraqi forces work to assume control of security from US forces, the US military has said that fighters would play on sectarian distrust before national elections are held in January 2010.