Baghouz, Syria -- Hundreds of people including ISIS fighters evacuated the terror group's last foothold in eastern Syria Monday hours after U.S.-backed Syrian fighters said they were forced to slow their advance because the extremists are using civilians as human shields. But despite the hinderance, spokesman for the Kurdish-led Syrian Democratic Forces Mustafa Bali tweeted that the battle to retake Baghouz, the last territory in Syria held by the Islamic State of Iraq and Syria (ISIS), was "going to be over soon."

Later Monday, an SDF official said some 500 people, including fighters, have surrendered and evacuated the village of Baghouz and its surrounding areas. Ciyager, the nom de guerre of an official with the Kurdish-led SDF, added that 200 more people were expected to evacuate Baghouz later Monday.

Dozens of men, women and children climbed hills on foot and were later seen getting into small trucks after they were searched by SDF fighters manning the evacuation corridor.

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An SDF spokeswoman said the offensive had slowed down but pressure was being kept up away from the corridor to prevent fighters from infiltrating or sabotaging the area. She spoke on condition of anonymity because she was not authorized to speak to the press.

The U.S.-backed forces resumed their offensive on Baghouz last Friday, after a two-week pause to allow for the evacuation of civilians.

Retaking the sliver of land would be a milestone in the devastating four-year campaign to end ISIS' self-proclaimed "caliphate" that once straddled a vast territory across both Syria and Iraq.

"We're slowing down the offensive" due to a small number of civilians held as human shields, Bali said. The previous night, an SDF statement said the Kurdish-led forces would continue their military campaign "to take control of the last ISIS-held pocket in Baghouz and to liberate the remaining civilians who are being used as human shields."

"In order not to harm them, we are advancing slowly but we assert that the battle of Baghouz will end in a short period of time," it said.

A young woman who left her home in Alabama to join ISIS but now wants to return to the U.S. with her young son told CBS News' Charlie D'Agata that after witnessing ISIS' brutality first-hand she tried to escape, but was caught.

"We were held hostage there basically," she said, "the only way to leave was to go through a field of IEDs, or snipers from ISIS shooting at you."

ISIS militants are desperately fighting to hang on to the last tiny piece of land in eastern Syria, deploying snipers and guided missiles and using dug-out tunnels for surprise attacks.

On Sunday, black smoke billowed over the besieged speck of land in the village after airstrikes hit several targets. SDF fighters had tightened the noose on the militants the day before, advancing from two fronts and cutting off their access to the river in Baghouz.