Iraqi authorities say insurgents have assaulted a mayor's office in a Sunni town just north of Baghdad, killing six.

Police officials say the assault by gunmen and a suicide bomber took place in Tarmiyah, a former insurgent stronghold about 50 kilometers (30 miles) north of Baghdad. A hospital official said there are five policemen among the dead, and another 18 were wounded.

All officials spoke on condition of anonymity because they were not authorized to speak to media.

Violence has spiked in Iraq following a security deadly crackdown on a Sunni protest camp in April. According to U.N. estimates, more than 8,000 people have been killed since the start of the year.