Islamic State militants on Friday captured the main government compound in Ramadi, the capital of Iraq's western Anbar province, after fierce clashes with security forces.

Ramadi's Mayor Dalaf al-Kubaisi says the militants raised the black flag of ISIS over the area after troops were forced to withdraw from the compound, which houses most of the city's government offices.

He said the IS militants, who also seized other parts of the city, are now attacking the Anbar Operation Command, the military headquarters for the province.

Dalaf said at least 10 policemen were killed in the fighting and dozens of other security forces were wounded. He said IS militants killed several captured policemen and army officers in the city, where most civilians have fled.

U.S. troops saw some of the heaviest fighting of the eight-year Iraq intervention in Anbar, and Ramadi was a major insurgent stronghold. The IS group captured the nearby city of Fallujah and parts of Ramadi in January 2014, months before its main sweep across northern and western Iraq.

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The IS assault on the Ramadi government compound began with three nearly simultaneous suicide car bombings. Two Humvees previously seized from the Iraqi army were used in Friday's attack, al-Kubaisi said.

Dozens of families were forced to flee their homes in the area, said Athal al-Fahdawi, an Anbar councilman.

The head of Anbar's provincial council, Sabah Karhout, appealed to the central government in Baghdad to send reinforcements and urged the U.S.-led coalition to increase airstrikes against the militants in Ramadi.

"The city is undergoing vicious attack by Daesh and we are in dire need of any kind of assistance," Karhout said, using the Arabic acronym for the IS group.