The terrorists were filmed running away from Manbij by a drone launched by the US-backed Syrian Democratic Forces.
The Kurdish-led group recaptured the strategically important town less than 20 miles from the Turkish border and close to an important bridge across the River Euphrates.
According to images posted by the SDF, black-clad ISIS fighters can be seen surrounding the civilian convoy as it makes its way out of the besieged city.
The ISIS terrorists are believed to be travelling on motorbikes and in cars along with the civilians.
The nature of the column prevented US aircraft - who could have wiped out the retreating terrorists in minutes - from attacking because of the risk faced by civilians.
The SDF, backed by US airstrikes, waged a two-month long campaign against ISIS in Manbij, forcing the terror group to flee.
Since their removal, the SDF have found several locations around the city which ISIS had used as a makeshift prison and others which were used as a temporary bomb factory.
The US military had aircraft on standby to wipe out the fleeing ISIS fighters but called off the strike mission due to the risk of civilian casualties.
It is understood that many of the terrorists went north towards Turkey, which is only 20 miles away.
Colonel Chris Garver, a spokesman for the U.S.-led coalition fighting ISIS, said commanders of the Syrian Democratic Forces made the decision to allow the convoy to pass.
Garver said it was highly likely that there were human shields in each of the terrorist vehicles.
He said: “They kept throwing civilians to basically walk into the line of fire, trying to get them shot to use that potentially as propaganda, we think.”
Manbij is a key victory for the SDF and the coalition, because it lies on a major supply route between the Turkish border and the city of Raqqa, the de facto capital of the ISIS caliphate.
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