How do I report child abuse without giving my name?

I suspect that my neighbor is abusing her daughter. She’s constantly screaming at her and I’ve seen bruising on her arms and legs. I don’t want anyone to know it’s me that called, though. I have to live next to this person and I don’t want her to retaliate against me. Is there some hotline I can call and still remain anonymous? If child protective services opens an investigation, can they force me to do an interview with them?