ISIS

Aid groups have been warning for months that the Mosul campaign could lead to a human catastrophe. Thursday provided a glimpse of the potential tragedy.

Already, 18,000 Iraqis have been displaced from their homes since the Mosul offensive was launched October 17, according to the International Organization for Migration. The agency warns that the weeks ahead will generate even greater displacement, especially now that the battle is being fought on the streets of Iraq's second largest city. It's believed as many as 1.5 million people are still living there.

"We are going to Mosul to free them from ISIS," Haider al-Abadi told a reporter for state-run Iraqiya TV at the Qayyara airbase south of the city.

He also had a message for the estimated 5,000 ISIS militants holed up in the city: "There is no way to escape, either surrender or die."

He urged the city's beleaguered residents, who have suffered under the ISIS yoke since June 2014, to stay indoors. He also said they should resist ISIS-propogated rumors, and do what they can to prevent ISIS from destroying the city's infrastructure.

The intent is sinister: Using civilians as human shields is ISIS's attempt to hold onto the city, the jewel of its self-proclaimed caliphate.

No one expected the militants to surrender Mosul without a hellish fight. But for Iraqis still living under ISIS control in the city and surrounding areas, every option now is grim.

They can try to flee but be branded by ISIS as "apostates," for which the penalty is death. Or they can potentially be seen as ISIS sympathizers in a new place and risk becoming victims of revenge crimes.

The terror group carried out the mass killings Wednesday, punishing people who had defied its orders, a spokeswoman for the UN human rights arm told CNN.

"ISIS executed 42 civilians in Hammam al-Alil, south of Mosul. Also on Wednesday ISIS executed 190 former Iraqi security forces for refusing to join them, in the Al Ghazlani base near Mosul," said Ravina Shamdasani of the Office of the UN High Commissioner for Human Rights.

Another 24 former Iraqi security forces officers were reportedly killed Tuesday, the office said.

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.

ISIS used a bulldozer to dump the corpses in a mass grave at the scene of the executions -- Mosul's defunct College of Agriculture in the north of the city, the intelligence source said.

The victims were all shot and some were children, said the source, who wanted anonymity because he is not authorized to speak to the media. CNN could not independently confirm the claim.

Artillery began firing on the city early on Monday, in a long-awaited assault from Kurdish Peshmerga, Iraqi government and allied forces.

Tanks are now moving towards the city, which has been held by IS since 2014.

The UN has expressed "extreme concern" for the safety of up to 1.5 million people in the area.

The BBC's Orla Guerin, who is with Kurdish forces east of Mosul, says tanks are advancing on the city, kicking up clouds of dust.

The terror group attacked a Kurdish defensive post on October 2 using a drone carrying "some sort of explosives," a senior Peshmerga officer said.

The drone killed two Peshmerga soldiers and injured two French military personnel north of Mosul, the Peshmerga officer said.

Images of the drone's remnants show "it appears to be a cheap Chinese drone, easily available on the market," CNN's Ben Wedeman said from Irbil, Iraq.

While the military did not specifically name the group, ISIS claimed responsibility for Friday's attack that left at least 12 soldiers and 15 of the assailants dead.

According to the army statement, released Saturday, the three-hour air operation targeted several concentrations of militants, destroyed ammunition and weapons storage facilities, destroyed seven vehicles and killed an unspecified number of militants.

Battle for control

The attackers hit the checkpoint using four-wheel drive vehicles, the Egyptian military said.

The Free Syrian Army (FSA), a Turkish-backed faction, took back Sunday the town of Dabiq from ISIS, Turkish state media and a monitoring group said.

The Syrian Observatory for Human Rights, a UK-based organization, said it received reports that groups of ISIS fighters had withdrawn from Dabiq overnight.

Though ISIS forces left, Turkish security sources told Anadolu's reporter the recapture of Dabiq was the hardest part so far for Operation Euphrates Shield.

"It's victory time," blares a headline on the newspaper-style leaflets, quoting Iraqi President Haider al-Abadi in remarks directed at Mosul's residents. "Time to celebrate a clean Iraq without 'Daesh' (ISIS) or any dark belief."

Another headline reads, "We are preparing to take action to free Mosul and regain security and stability in the region."