Scores of gunmen took over a federal police headquarters in northern Iraq on Friday before ramming a tanker laden with explosives into the building, killing at least 15 people, a government official said, Reuters reported.
The battalion commander and four high-ranking officers were among the dead, trapped under debris when the force of the blast brought the building down on them in the village of Injana, the official said. The other dead were also police.
The mayor of the nearby town of Sulaiman Pek, 160 km (100 miles) north of Baghdad, said security forces later regained control over the village.
Islamist militants occupied Sulaiman Pek last month and raised the black flag of the Sunni Islamic State in Iraq and the Levant (ISIL), a group inspired by al Qaeda, over it.
Security officials said the tanker bombing might have targeted the dead battalion commander, Brigadier General Raghib Ali, in revenge for his role in driving the militants out of Sulaiman Pek.
ISIL, which is also active in neighboring Syria, has regained momentum in Iraq over the past year and is one of a number of insurgent and tribal groups that stormed the cities of Ramadi and Falluja in the western province of Anbar in January.
In Ramadi on Friday, six people were killed when a suicide bomber blew himself up inside a mosque where a funeral was being held for an officer who died in a roadside bombing earlier this week, medical and security sources.
In Falluja, about 300 militants paraded through the main streets late on Thursday dressed in black and bearing ISIL's banner. They showed off military Humvees, armored vehicles and some weapons they said they had taken from Iraqi soldiers during the fighting.
Residents of Falluja lined the road, welcoming them with cries of "you are heroes!" and showering them with chocolates.
Prime Minister Nouri al-Maliki, a Shi'ite Muslim, has declared war on Sunni militants, appealing for arms and international support to help quell an insurgency he paints as an extension of the civil war in Syria.
Maliki's critics say his own sectarian-oriented policies have marginalized Iraq's country's once-dominant Sunni minority and created the conditions for militants to thrive.