Islamic State militants have seized the main government building in Ramadi, the capital of Iraq's largest province.
As many as six suicide car bombs and mortars were used in the assault on the compound that houses the main police Head Quarters and governor's office.
At least 50 police officers are reported to have been taken prisoner at the site.
IS and Iraqi troops have been battling for months to take control of the strategically important Anbar province.
This latest attack comes a day after Islamic State put out an audio message it claimed was from its leader, Abu Bakr al-Baghdadi, who Iraq had said was seriously wounded in a coalition air strike in March.