I would immediately contact both the school counselor and your child's teacher. Perhaps send them both an e-mail asking to set up a meeting with them, and discuss this face-to-face. My daughter also was bullied in 1st grade. It was shocking, and even the teacher, who was seasoned and had seen so much, was shocked at the level of the meanness. My daughter was bullied because she was the only girl in the class who would not do whatever the bully told her to do...that is, the bully also bullied the others, but to a lesser extent because they did what she wanted. My daughter dances to a different drummer, and that helped her because she was able to block out some of the meanness, but she was stunned, daily, that someone could be so mean. (My daughter is very kind.) We immediately got the school involved, and it was helpful. The teacher promised us, at our spring conference, that the girl and my daughter never would be in the same class again in the elementary school. She then told us that she had to separate the bully from all but 1 girl in the class. Then the 2nd grade letters arrived in August, and the bully called my daughter to ask her which teacher she had. Of course, I knew they wouldn't have the same one, but I handed the phone to my daughter. I could hear the girl on the other end say, "It's so strange. NO ONE is in my class!"
Somehow, my daughter loved going to school every day, in spite of the mean kid(s). Every day I would tell her that the bullying is not about HER but is about the low self esteem of the girl who was bullying.
Several years later we learned that there were some major issues going on in the bully's home. No excuse for bullying, but there seemed to be a reason that this girl was acting this way towards others.