advice please

My daughter came to me yesterday and told me that she didn't like this little girl at school because she's dark brown. I was in shock and upset because I've thaught my daughter to treat everyone equally. My daughter is brown herself, she's of Hispanic descent. Although she's light skinned I've tried to teach her about equality. I had a long conversation with her and turns out some of her little friends (they're in kindergarten) didn't like this girl and have been talking badly and my daughter started listening into it. I'm so disappointed In her because even if she's only 5 years old she knows right from wrong. She started crying saying that her friends wouldn't like her anymore if she talked to that other little girl. I'm just at loss of how to go about this. Any advice would be greatly appreciated. Thanks in advance