According to the BBC tens of thousands of people have fled their homes in northern Syria, as Turkish forces step up their cross-border offensive on Kurdish-held areas.
Turkish troops have encircled the border towns of Ras al-Ain and Tal Abyad and aid agencies fear the exodus could reach hundreds of thousands.
International clamour has increased for Turkey to halt the attack.
Turkey has defended its bid to create a “safe zone” free of Kurdish militias which could also house Syrian refugees.
Turkey regards the Kurdish militias of the Syrian Democratic Forces (SDF) – which have controlled the cross-border areas – as “terrorists” who support an anti-Turkish insurgency.
The SDF have been key allies of the United States in the battle against the Islamic State (IS) group.
However, it was after President Donald Trump’s decision to pull US troops out of the area that Turkey launched its assault, sparking SDF accusations they had been “stabbed in the back”.
Many in the US, including some of Mr Trump’s Republican allies, say the withdrawal effectively gave Turkey a green light.
One major concern for the international community is the fate of thousands of suspected IS prisoners, including many foreign nationals, being guarded by Kurdish-led forces in the region.
The International Rescue Committee aid organisation said that 64,000 people had already reportedly fled their homes. The UK-based monitoring group, the Syrian Observatory for Human Rights, gave a similar figure.
The IRC’s Misty Buswell said: “If the offensive continues it’s possible a total of 300,000 people could be displaced to already overstretched camps and towns still recovering from the fight against IS.”
Another group of 14 humanitarian organisations, including the Mercy Corps, warned the figure could be 450,000.
Ms Buswell said IRC teams remained on the ground, although other reports suggest some aid groups have pulled back across the Turkish border.
Sevinaz, a resident of Ras al-Ain, told the BBC on Thursday morning: “I am outside the town with my sick mother. My brother is inside. I have been informed that my cousin might have been martyred. There is no safe place for anybody.
“I’m concerned about it being the last time that I see my city.”