MOSUL, Iraq (Reuters) - From a distance, the exhausted Iraqis fleeing parts of Mosul controlled by Islamic State appeared to be pushing their worldly possessions on handcarts.

By the time they reached Reuters journalists it was clear that their cargo was far more precious, and more tragic. One man lifted a grubby, fluffy blanket to reveal the dust and blood-covered body of a child, one of several piled up on the cart.

“This is my son. He is gone,” he said, describing how his family’s home had been hit by an air strike. Iraqi helicopters have been pounding west Mosul with missiles as its troops push into Islamic State’s last holdout in Iraq.

“This happened because of air strikes. These were in their homes and the air strikes killed them,” the man said, showing other small bodies, cut by shrapnel or debris, on the cart.

He said the strike had happened three days earlier close to Mosul’s train station, an area the family had only just moved to after fleeing their home in the Wadi Hajjar neighborhood where fighting had become too intense.

Reuters could not verify his account.

Other families trekking down the road towards buses sent to take civilians to camps used similar carts to transport elderly relatives.

They will join the 255,000 or so people already displaced from Mosul and surrounding areas since October, when the U.S.-backed push against Islamic State began - creating a huge challenge for aid agencies delivering food and shelter to people who have known years of suffering.

Iraqi forces on Friday advanced closer to the al Nuri mosque from which Islamic State declared its caliphate nearly three years ago.