Ukrainian girl who went viral for singing "Let It Go" in bomb shelter performs for thousands in Poland

The young Ukrainian girl who went viral for singing a hit song from the movie "Frozen" in a Kyiv bomb shelter has performed her country's anthem live on stage at a charity concert in Poland, where she is now a refugee.

Thousands of people waved lights in the darkened stadium in Lodz, Poland as 7-year-old Amellia Anisovych sang on Sunday evening. The charity event raised more than $380,000. 

She wore a traditional Ukrainian embroidered dress and sang in the same clear voice that could be heard in a mobile phone video when she sang "Let it Go" from the bomb shelter.

She fled to Poland and is now with her grandmother and her brother, but her parents remain in Kyiv.

The United Nations said Sunday that Russia's war in Ukraine has forced 10 million civilians to flee from their homes, including about 3.5 million who have sought refuge in other countries already.

In Poland, which alone has taken in more than 2 million Ukrainian refugees,  the U.N. refugee agency has established a direct cash aid program along with the Polish charity Caritas Polska to provide the displaced with funds to cover basic needs.

Almost two dozen U.N. agencies are still operating in Ukraine, and efforts to help those displaced and trapped in besieged cities continue to scale up. 

CBS News correspondent Pam Falk contributed to this report.