As the Turkish invasion in northern Syria proceeds, the region appears to have descended into violent chaos, with videos emerging of Turkish proxies slaughtering US allies.

About 700 women and children with links to the terrorist group ISIS left a Kurdish-run detention camp after a Turkish airstrike nearby prompted about 13,000 people, mostly displaced refugees, to flee.

The humanitarian aid group Save the Children said it appeared that all the women and children, who were being held in a secure facility at the camp, had left. It was unclear whether they escaped or were apprehended by coalition forces who brought them to a central facility.

The Turkish invasion began shortly after President Donald Trump announced that US troops would be repositioning away from Kurdish forces, who have been US allies in the fight against ISIS.

On Sunday, US Defense Secretary Mark Esper announced that the remaining 1,000 US troops in northern Syria would be withdrawn as intelligence indicated a more expansive Turkish invasion and a Kurdish counterattack in conjunction with Syrian and Russian forces.

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As the Turkish invasion in northern Syria continues into its fifth day, following President Donald Trump's announcement that US forces would be repositioned away from Kurdish allies, reports of violent chaos have emerged from the region.

A US official told CNN on Sunday that the campaign to defeat the terrorist group ISIS in Syria was "over for now" and that ISIS "has a second lease on life with nearly 100,000 [people] who will rejoin their jihad." The official added that "US policy has failed."

The US State Department has acknowledged reports that Havrin Khalaf, the civilian secretary-general of the Future Syria Party, the Kurdish movement, was captured and killed by Turkish-backed Syrian opposition fighters and that other Kurdish fighters were killed by Turkish proxies.

Read more: The US shared intelligence with Turkey that may have helped it target the Kurds in Syria

Videos have surfaced showing Turkish-backed rebel forces slaughtering Kurdish fighters. In one video published by The New York Times on Saturday, two Syrian Arab fighters repeatedly shoot a Kurdish prisoner on the ground with his hands tied behind his back.

On Twitter, a Turkish member of Parliament from President Recep Tayyip Erdogan's party condemned the execution of unarmed war prisoners.

Turkey considers the Syrian Kurdish People's Protection Units, or YPG, a terrorist organization. It is the dominant force of the Syrian Democratic Forces, which had partnered with the US to dismantle ISIS's hold in Syria.

On Sunday, US Defense Secretary Mark Esper said the remaining 1,000 US troops in northern Syria would be withdrawn. US officials later told The Daily Beast they would just be moved farther from the advancing Turkish forces. A Turkish airstrike nearly hit a small group of US troops stationed in Syria on Friday.

A Turkish army armored vehicle advances in Syrian city of Tel Abyad, as seen from the Turkish border town of Akcakale, on Sunday. The military action is part of a campaign to extend Turkish control to more of northern Syria, a large swath of which is held by Syrian Kurds, whom Turkey regards as a threat. Photo by Burak Kara/Getty Images

Kurdish-held territory in northern Syria has been hit by Turkish airstrikes, freeing some ISIS prisoners in the process

On Saturday, the Turkish military said it had captured a key town on the Turkey-Syria border that had been under Kurdish control.

Esper said on Sunday that intelligence indicated that in addition to crossing the northern Syrian border along Turkey's southeastern region, Turkey would advance even farther south and west than originally planned.

Trump, who has called the Turkish invasion a "bad idea," first announced the withdrawal of US troops in Syria after a phone call with Erdogan earlier this month. The Times also reported that the US government shared intelligence with Turkey that might have helped it target the Kurdish forces, after a disagreement between Trump and Erdogan over the US arming Kurdish forces.

Turkish airstrikes have hit near and in towns south of the border, including near a camp that housed about 13,000 people, mostly displaced refugees. Within the camp was also a secure facility that held more than 700 women and children with links to ISIS.

Read more: The US is preparing to pull its remaining 1,000 troops out of northern Syria as the Turkish offensive against the Kurds moves forward

The humanitarian agency Save the Children said it appeared that all those women and children had left the secured facility and that some likely escaped while others were apprehended by coalition forces and taken to a central facility.

Other reports and videos have suggested that more ISIS prisoners, including dangerous combatants, may have escaped amid airstrikes in northern Syria.

Kurdish forces guarded ISIS prisoners in the region, but their ability to do so has been greatly impeded by the Turkish invasion.

Esper also told CBS News on Sunday that Kurdish forces were planning a counterattack against the Turkish military and soliciting an allegiance with Syrian fighters and Russian forces. US forces stationed in northern Syria could be caught in the crosshairs, prompting the withdrawal, he said.

Another US official told NBC News that a confrontation could occur between Turkish proxies and US troops unless the Turkish invasion is halted, as the proxies advance south using extremist, violent tactics.