ERBIL, Iraq, July 23 (Xinhua) -- Security forces on Monday sealed off a government building in the northern city of Erbil, after two unidentified gunmen stormed into the building.

The incident took place at around 7 a.m. local time (0500 GMT), when two gunmen wounded a policeman at the gate, broke into the building and fired with small arms, Kurdish media net Rudaw cited deputy governor Tahir Abdullah as saying.

Kurdish security forces rushed to the scene, cordoned off the area, and started exchange fire with the attackers, Abdullah added.

Kurdish special forces later broke into the building, searching for the attackers room by room, he said.

As the largest city in northern Iraq, Erbil is both the capital of its namesake province and the semi-autonomous region of Kurdistan.

No group claimed responsibility for the attack in Erbil, some 350 km north of Iraq's capital Baghdad, which has been relatively calm since the U.S.-led invasion in 2003.