We had a similar problem with KT in preschool. All of a sudden, 1/2 way through her second year of being at the same preschool, she didn't want to go anymore. Red Flag. Turns out one of the little boys was hitting her when the teacher wasn't looking.
We had a somewhat similar problem with KT in kdg. A little boy who had been in "anger management counseling for 9 months after his father had been tragically killed in a bar fight" targeted KT. Told her he hated her and was going to bring a gun to school and kill her.
I found out 2 days after it happened....and it was KT who told me. I asked the teacher about it and she told me that was exactly what happened, but she talked to the two of them, and this little boy said he was sorry and he really wouldn't do that. And she told me "he is such a sweet boy, I don't think he'd ever do that." And I said "is THAT the soundbite you want to hear played on the 6:00 news after my daughter is shot???"
The next day our "notification to homeschool" went into the superintendant and KT hasn't gone back since.