Hundreds of civilians have been executed by the men of the ISIS as they were used as human shields during a recent attack in Mosul.
CNN reported that those killed on Thursday and Friday had been rounded up near and in the city for use as human shields against attacks that are forcing ISIS out of the southern sections of Mosul, the source explained.
It was further gathered that ISIS used a bulldozer to dump the corpses in a mass grave at the scene of the executions that took place at the Mosul's defunct College of Agriculture in the north of the city.
The United Nations earlier said it is "gravely worried" that ISIS has taken 550 families from villages around Mosul and is using them as human shields as Iraqi and Kurdish forces battle the terror group for control of Iraq's second-largest city.
200 families from Samalia village and 350 families from Najafia were forced out on Monday and taken to Mosul in what appears to be a policy in which ISIS used in prevent civilians from escaping.
Meanwhile, ISIS militants attacked security buildings in Kirkuk, 175 kilometers (109 miles) southeast of Mosul.
Expressing concern, Zeid Ra'ad Al Hussein, UN High Commissioner for Human Rights, said his office had evidence of several instances since Monday where ISIS forced civilians to leave their homes in outlying villages and head to Mosul. It also had received reports that civilians suspected of disloyalty had been shot dead.
"We are gravely worried by reports that (ISIS) is using civilians in and around Mosul as human shields as the Iraqi forces advance, keeping civilians close to their offices or places where fighters are located, which may result in civilian casualties," Zeid said.
"There is a grave danger that (ISIS) fighters will not only use such vulnerable people as human shields but may opt to kill them rather than see them liberated," he said.
CNN further reported that Al Hussein's office is examining reports that ISIS shot dead at least 40 civilians in a village outside Mosul.