Islamic State militants have killed 500 members of the Yazidi ethnic minority, including some women and children who were buried alive, Iraq’s human rights minister said on Sunday.

Mohammed Shia al-Sudani told Reuters that another 300 women were kidnapped and forced into slavery as the Sunni jihadist fighters rampaged across the north of the country.

“We have striking evidence obtained from Yazidis fleeing Sinjar and some who escaped death, and also crime scene images that show indisputably that the gangs of the Islamic State have executed at least 500 Yazidis after seizing Sinjar,” Sudani was quoted as saying.

“The terrorist Islamic State has also taken at least 300 Yazidi women as slaves and locked some of them inside a police station in Sinjar and transferred others to the town of Tal Afar,” he added. “We are afraid they will take them outside the country.”

Islamic State captured Sinjar and other ancient hometowns of the Yazidis, a religious group that the jihadists view as “devil worshipers.” Some 40,000 Yazidis fled to nearby Mount Sinjar without adequate supplies in the height of summer, where they now face death by starvation and thirst or by the hands of the Islamic militants who have laid siege to the mount.

“Some of the victims, including women and children, were buried alive in scattered mass graves in and around Sinjar,” Sudani said. “In some of the images we have obtained, there are lines of dead Yazidis who have been shot in the head while the Islamic State fighters cheer and wave their weapons over the corpses. This is a vicious atrocity.”

The plight of the Yazidis, thousands of whom have managed to escape into Kurdish-held territory in northern Iraq, prompted an international outcry. Last week, US President Barack Obama authorized US airstrikes to protect American interests in the region, and warplanes have since struck Islamic State positions and military equipment to try to break the siege. The US and Britain have also begun airlifts to drop humanitarian supplies for the stranded Yazidis.

Sudani appealed to the international community to help defeat the Islamic militants before they spread beyond Iraq.

“The international community should submit to the fact that the atrocities of the Islamic State will not stop in Iraq and could be repeated somewhere else if no urgent measures are taken to neutralize this terrorist group,” he said.

On Sunday, a senior Kurdish military official said his forces had retaken two towns from the Sunni militants who have seized large parts of northern Iraq.

Brig. Gen. Shirko Fatih said the Kurdish fighters were able to push the militants of the Islamic State group out of the villages of Makhmour and al-Gweir.

The retaking of the two towns in Nineveh province is significant because it is the first victory by the Kurdish forces, known as Peshmerga, which until now have been in retreat.

The radical Sunni fighters seized Mosul in June and then went on to take even more towns, sending tens of thousands of minorities fleeing into the Kurdish-controlled region.