Five Assyrians disappeared nearly four days ago from an orphanage in Mosul, Iraq. Two nuns are among the missing.

Sister Miskintah, Sister Utoor Joseph, Hala Salim, Sarah Khoshaba, and Aram Sabah have not been heard from since they returned to the Nineveh Province capital to check on an abandoned orphanage. Mosul fell to the Islamic State of Iraq and al-Sham (ISIS) terrorist group weeks ago.

The Chaldean nuns ran the all-girl orphanage near Miskintah Church in Khazraj, Mosul. The women and children escaped to Dohuk when ISIS ravaged the city, but returned to Mosul late Saturday. No sign of them has been discovered.

The Assyrian media reported that the women may have been kidnapped by ISIS.

The Sunni Muslim extremists have persecuted, raped, and killed Christians and Shiite Muslims across Iraq and Syria. Churches and Shiite shrines have been bombed, and hundreds of thousands of Iraqis have fled the area because of the violence.

Women and children are not spared in the attacks, and survivors of assaults in Brawawchli, Chardaghli, Karanaz, and Bashir said that the militants shot villagers at point-blank range.

"You cannot imagine what happened, only if you saw it could you believe it," Hassan Ali told the Associated Press from Kirkuk, where many fled.

"They hit us with mortars and mortars, and the families fled, and they kept hitting us. It was completely sectarian. The Shiites, out."

The survivors say the militants shouted "God is great!" while they carried out their attack.

"All shot in the head," one person told the Washington Post.

"Please tell the world," another pleaded. "It was a savage massacre."

ISIS seeks to establish a Sunni Muslim reign across Iraq and Syria. The terrorist group, led by Abu Bakr al Baghdadi, has increased in power substantially since the withdrawal of U.S. troops from Iraq in December 2011.

ISIS controls the Iraqi cities of Mosul, Baiji, and Fallujah, as well as parts of Syria. The group has also posted photos and videos online showing Iraqi policeman and civilians being slaughtered.

The United Nations reported Tuesday that over 2,400 people were killed in Iraq last month.