The insurgent group, which swept through northern Iraq in June almost unopposed by Iraq’s US-trained army, poses the biggest challenge to the stability of the country since the fall of Saddam Hussein in 2003.
After thousands of Iraqi soldiers fled the Islamic State offensive, Shi’ite militias and Kurdish fighters have emerged as a key line of defence against the militants, who have threatened to march on Baghdad.
Kurdish forces poured in reinforcements, including special forces, to the town of Zumar to battle Islamic State fighters who had arrived from three directions on pickup trucks mounted with weapons, residents said.
The militants later hoisted their black flag over buildings in Zumar, a ritual that has in the past been followed by the mass execution of captured opponents and the violent imposition of an ideology that even al-Qaeda finds excessive.
Residents fled Sinjar
The Islamic State later also seized the town of Sinjar, where witnesses said residents had fled after Kurdish fighters put up little resistance against the militants.
Islamic State has stalled in its drive to reach Baghdad, halting just north of the town of Samarra, 62 miles north of the capital.