she should be examined by a doctor. physical evidence would make it a lot easier.
also do remember that kids can lie, but always give them the benefit of the doubt. if you really are that worried about it then send her someplace else.
Well, if this were me, I would assume that something had happened. I think children may not always get all the details straight, but it does sound like some sort of innappropriate touching has happened. I tend to be overly cautious, but my first reaction would be to have her see a professional who is properly trained to find out this type of information in young children. I would also have a very serious conversation with the school. And truth be told, I would probably remove my child from the school until you can get to the bottom of things.
I wouldn't necessarily assume the worst - it could easily have been another young child just being silly, and I wouldn't jump to molestation by an adult or anything. But I know that I would have to try to get to the bottom of things, and ensure my child was fully protected.
Best of luck to you, and i hope you get your answers quickly and that your daughter is doing well.
Well being a serious matter your daughter is old enough to tell you someone touched her so i would consider talking to the teacher and if something isn't right I would have the police investigate because remember that their are more children who might be going through the same things.