(CNN) — ISIS rounded up and killed 284 men and boys as Iraqi-led coalition forces closed in on Mosul, the terror group’s last major stronghold in Iraq, an Iraqi intelligence source told CNN.
Those killed Thursday and Friday were used as human shields against attacks forcing ISIS out of southern parts of Mosul, the source said.
ISIS dumped the corpses in a mass grave at the defunct College of Agriculture in northern Mosul, the intelligence source said.
The victims — some of them children — were all shot, said the source, who asked for anonymity because he is not authorized to speak to the media. CNN could not independently confirm the killings.
• Kurdish officials accused Sunni Arabs in Kirkuk of supporting ISIS a day after attacks killed dozens.
• A large-scale offensive began Saturday to retake Hamdaniya; Iraqi troops also advanced on Tal Kayf.
• Iraqis displaced by the Mosul offensive are seeking shelter in camps, the UN refugee agency said.
Iraqi forces move on Hamdaniya
The Iraqi military launched a large offensive early Saturday to retake Hamdaniya — also known as Qaraqosh — from ISIS, the Iraqi Joint Operations Command center said.
The city is about 15 kilometers (nine miles) southeast of Mosul.
Iraqi troops entered the al-Askary neighborhood and liberated the mayor’s building and the main hospital, raising the Iraqi flag over those buildings, Lt. Gen. Qassim al-Maliky said.
At least 50 ISIS militants were killed and some of their equipment destroyed, he added.
Iraqi security forces and Peshmerga — as the Kurdish fighters are known — have made progress and isolated Hamdaniya, a US military official said in Baghdad, speaking on background.
Tal Kayf is next target
Iraqi troops are also advancing toward Tal Kayf and plan on storming the Chaldean town, the Iraqi Joint Operations Command said Saturday.
Tal Kayf is about 10 kilometers (six miles) north of Mosul.
It’s the closest Iraqi security forces have come to Mosul, a CNN analysis indicates.
The US military official said US and coalition aircraft were providing air support as needed Saturday. The official said land forces were working through “a hard outer crust,” and resistance would intensify as the offensive neared Mosul.
The official said ISIS fighters had infiltrated towns cleared earlier, including Bartella, requiring renewed efforts to combat them.
Clashes in Kirkuk, Laylan
Kurdish security forces were going house to house Saturday in Kirkuk following a major ISIS attack a day earlier. Kirkuk is 175 kilometers (109 miles) southeast of Mosul.
Kirkuk’s police chief said 48 ISIS militants had been killed during hours of clashes.
Security officials told CNN that at least 40 others had been killed and 76 wounded in the attack, the majority of them Kurdish Peshmerga.
The ISIS attacks continued in the area Saturday, with an attempt to infiltrate the town of Laylan, 20 kilometers (12 miles) southeast of Kirkuk. Nine militants were killed, according to the mayor of Laylan, Mohammed Wais, and some security force members were injured.
Kurdish President Masoud Barzani described ISIS’ attack on Kirkuk as “a failed attempt by terrorists to make up for the defeats they have suffered at the hands of the Peshmerga on the front line.”
Previous attacks by ISIS militants on Kirkuk have been attempts either to capture the city from the Peshmerga or divert Kurdish troops from the fight in Mosul.
About 4,000 families are housed in four camps for internally displaced people in Laylan, said Ammar Sabah, director of the Displacement and Migration Department in Kirkuk.
Kurdish officials accuse local Arabs of helping ISIS
In the wake of the Kirkuk attack, Kurdish officials accused local Arabs and some displaced in camps around the city of helping ISIS.
Kirkuk’s police chief, Brig. Gen. Khatab Omar, said the militants had probably infiltrated the 600,000 internally displaced in and around the city.
Gen. Hallo Najat, another police official, told local media to expect further fighting because 30% of the Arabs there supported ISIS rather than the government or Kurdish authorities.
Najmaldin Karim, Kirkuk’s governor, said: “We have prior knowledge that an operation like this could happen; we were preparing for it, but the timing was not known exactly.”
He said a curfew would remain in force for another day and urged the internally displaced community in Kirkuk to help track down militants.
US defense chief visits
US Secretary of Defense Ash Carter arrived Saturday in Baghdad on an unannounced visit.
Carter was expected to receive an update on the Mosul offensive and meet with Iraqi Prime Minister Haider al-Abadi before attending a troop event.
US forces in Iraq are providing air support for the Mosul operation as part of an international coalition. US special operations forces are also advising Iraqi and Kurdish units on the ground.
UN ‘gravely worried’ over human shield use
The United Nations expressed concern Friday that ISIS has taken 550 families from villages around Mosul to use as human shields.
Two hundred families from Samalia village and 350 families from Najafia were forced out Monday and taken to Mosul in “an apparent policy by ISIS to prevent civilians escaping,” Ravina Shamdasani, deputy spokeswoman for the UN Human Rights Office, told CNN.
Zeid Ra’ad Al Hussein, the UN High Commissioner for Human Rights, said, “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.”
Iraqis flee violence
The first influx of Iraqis — 144 people — arrived at a camp in Zelikan, set up to shelter what is expected to become a flood of families displaced by the Mosul offensive, the UN refugee agency said Saturday.
UN data indicate some 3,900 people — or 650 families — have so far been forced from Mosul and Hamdaniya districts, agency spokesman Adrian Edwards told a news briefing Friday in Geneva, Switzerland.
The UN refugee agency is working to establish 11 camps, five of which are already in place, to house those forced from their homes by the battle. The camps will have capacity for about 120,000 people, the agency said.
Up to 600,000 could be helped if the refugee agency obtained sufficient funding, it said. Mosul is believed currently to have a population of about 1.5 million people, it added.
Charity Oxfam warned Saturday that more must be done to provide safe routes for those fleeing the conflict.
People who escaped from Hawd, 50 kilometers (about 30 miles) south of Mosul, told Oxfam that many civilians had been injured.
A woman told Oxfam her children had respiratory issues after breathing in thick smoke from oil wells that ISIS militants set afire to provide cover from coalition air attacks.