Exclusive: Iraqis pack up a lifetime as they flee ISIS-held Mosul in the dark of night

The soldiers are on edge, peering nervously into the dark. They can make out the sound of people -- they can never know whom -- approaching their position on this mountainside overlooking Mosul.

Then, in groups of two or three, they emerge from the night: men, women, children, the elderly.

Some can barely walk. They've been on their feet for hours, and need to be carried the rest of the way.

It's the same routine, night after night.

To get to the Kurdish front lines in northern Iraq, people fleeing Mosul must avoid detection by ISIS militants, step carefully through minefields, and be ready to find shelter if mortar rounds come crashing down. For men, capture by ISIS could mean punishment if they're lucky -- but more likely it will mean death.

By the time they reach safety, some have been walking for four or five hours. Adults must carry the young children. They arrive thirsty, hungry and exhausted. Walking by night, however, is preferable to doing it by day, when they can be picked off by ISIS snipers or fall prey to the withering heat, with daytime temperatures well over 110 degrees Fahrenheit (around 45 degrees Celsius).