BAGHDAD — The gunmen had surrounded the village for more than a week, refusing to let residents leave and saying they had limited time to save themselves by converting to Islam.

When that time ran out, fighters from the Islamic State in Iraq and Syria stormed in, killing the men and rounding up the women and children, a survivor and Iraqi officials said Saturday.

The extent of the killings on Friday in Kocho, a tiny, isolated village in northern Iraq that is home to members of the Yazidi religion, remained unclear on Saturday night. Some officials said they believed that at least 80 people had died, although no one had been able to visit the site to assess the damage.

The killings were likely to heighten international concern about the plight of religious minorities in parts of northern Iraq where ISIS has been fighting Iraqi forces and Kurdish militias.