Iraqi forces moved more than 1,000 people out of villages near Mosul that were recently retaken from the Islamic State group for their safety, officials said Wednesday, as witnesses and Iraqi commanders said the militants have driven hundreds of civilians into the city, using them as human shields.

Here are the major developments on the 10th day of the Mosul offensive

CIVILIANS DISPLACED

Witnesses and Iraqi commanders tell The Associated Press that IS is withdrawing from villages south of Mosul, taking civilians with them to use as human shields and leaving behind explosive booby-traps to slow the advancing troops.

"IS took all of us from our homes at gunpoint and told us they were taking us with them to Mosul," said Ahmed Bilal Harish, who later escaped when airstrikes scattered the militants, and is now at a camp for displaced people south of Mosul.

The U.N. High Commissioner for Human Rights says Iraqi forces found the bodies of 70 civilians who were shot dead in a village south of Mosul and that IS killed 50 former Iraqi police officers they were holding near the city. It says the militants killed 15 people in another village and threw their bodies into a river, and dragged six more around the village with a car.

It also reported the forcible displacement, saying the militants shot dead three women and three girls who were lagging behind because one of the girls was disabled.

The Iraqi special forces meanwhile said residents of Tob Zawa and other recently retaken villages east of Mosul were taken to a camp in the nearby Khazer region for their safety. The International Organization for Migration says around 9,000 people have been displaced since the operation to retake Mosul began on Oct. 17.

BARRIERS AND TUNNELS

The militants have had months to prepare for the long-awaited operation and are believed to have developed extensive defenses in and around the city.

The U.S. military says they have erected berms and trenches, and dug out an extensive tunneling system, with some tunnels extending nearly two kilometers (over a mile). Iraqi special forces operating east of Mosul said they had found a large tunnel network extending toward the city, with some passages wide enough to allow the fighters to ride motorcycles through them.

The U.S. military says Iraqi forces have found homes near Mosul where the lights are wired with explosives that detonate if the switch is flipped. Inside Mosul, IS has set up large concrete barriers known as T-walls, blocking off several streets.

The operation to retake Mosul, Iraq's second largest city, is expected to take weeks, if not months. The fighting thus far has been focused on a belt of sparsely populated farming communities on the Ninevah plain outside the city.