Updated

Iraqi officials say militants have killed 15 troops in an attack overnight on military barracks in a remote area in the country's north.

Police officers said on Tuesday that an unknown number of gunmen attacked the barracks in Ayn al-Jahish village, outside the northern city of Mosul late the previous night.

A medical official says eight of the soldiers were beheaded while the others were killed by gunfire. All officials spoke on condition of anonymity because they are not authorized to talk to media.

Mosul is a former insurgent stronghold, located about 360 kilometers (225 miles) northwest of Baghdad.

The brazen attack comes amid a surge in violence to levels unseen in Iraq since 2008. It's been a most serious challenge to the Shiite-led government's efforts to achieve stability.