Suicide bombers and gunmen attacked a police intelligence headquarters in the northern Iraqi city of Kirkuk on Wednesday, killing at least six people and wounding dozens more, a health official said, Reuters reported.
Security forces and attackers engaged in a two-hour gun battle at the complex where explosions could be heard, police said.
Hospitals in the city, 250 km (155 miles) north of Baghdad, counted six people killed and 47 wounded, said Sabah Amir Ahmed, head of the health directorate in Kirkuk.
No group immediately claimed responsibility for the attack, but Sunni Muslim insurgents linked to al Qaeda have regularly hit targets linked to the Shi'ite-led government and security services since the start of 2013.
Areas around Kirkuk are strongholds of al Qaeda, according to security officials.
On Tuesday 12 people were killed in two similar attacks in northern Iraq targeting a government complex and a police building.
Violence in Iraq has intensified along with the conflict in neighboring Syria and is expected to escalate ahead of parliamentary elections in April next year.