Having taken scores of Kurdish villages in the surrounding area, ISIS fighters are increasingly surrounding the key Kurdish city of Ayn al-Arab, along the Syrian-Turkish border.

Border crossings are always a prize for militants, and ISIS has tried to take Ayn al-Arab repeatedly, leading the various Kurdish militias to mobilize large “calls to arms” to defend the city.

Locals aren’t willing to bet that’s going to work again this time, however, and they are fleeing en masse into neighboring Turkey. An estimated 100,000 civilians have fled Ayn al-Arab already.

That number is expected to rise as ISIS continues to near the city itself, and the Kurdistan Workers Party (PKK) continues to urge Kurds in southeastern Turkey to take up arms to defend the city.