The charity estimated that around 1,000 children had been in the makeshift complex in Calais, a longtime launchpad for migrants to Britain which French authorities have begun tearing down.
"It's very scary, I think, for kids particularly. You see them coming in with bulldozers. This is where children have been living for weeks and months in some cases," Carolyn Miles, the president and CEO of Save the Children, told AFP at a New York gala Tuesday night to support the group.
Save the Children had earlier urged France to hold off on the demolition.
Miles said Britain and France were both paying attention to unaccompanied children but urged the governments to ensure a clear path forward, especially for children who ultimately are not admitted to enter Britain.
It is "really important, especially now when things are so chaotic there, that we keep these children safe and we make sure that they get the opportunity that they deserve to go on from there," she said.
Some 6,000 to 8,000 migrants, mostly Afghans, Sudanese and Eritreans, had been staying in the squalid camp with hopes of crossing the Channel to find better lives in Britain.
The gala honored Somali-born supermodel Iman, the widow of rock legend David Bowie, who has been active in Save the Children projects in Africa. Hollywood star Jennifer Garner served as the evening's host.
Country singer Jennifer Nettles, who performed at the gala, said she regretted that the crisis of migrants from war-torn Syria and elsewhere did not receive more attention in the United States.
"I wish that it were more in our public eye and therefore on our public heart," she said.
"But I also think that at the same time... people don't know what to do about it. And you either go numb because you feel helpless, or you feel completely outraged but you still don't know what to do."
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