Officials and residents say Islamic State militants have seized two more towns in northern Iraq.
The towns of Zumar and Sinjar fell on August 3 after fierce clashes that erupted the previous day between the extremist insurgents and Kurdish security forces.
Sinjar has sheltered thousands of people who were displaced by an offensive launched by the Islamic State, previously known as ISIL, in the region nearly two months ago, seizing large swaths of territory.
Sinjar is also a historical home for the Yazidis, a Kurdish-speaking minority and religious sect.
In a statement on August 3, the top UN envoy in Iraq, Nikolay Mladenov, said "a humanitarian tragedy is unfolding in Sinjar."
The UN said it was concerned about the safety of hundreds of families who had fled Sinjar for the relative security of a nearby mountain where they were surrounded by the militants.