Amber Lee Gutierrez, 33, has been charged with felony corporal injury to a child. Police say her daughter arranged a fight with Teah LaGranda, a classmate from Dana Middle School, on Jan. 14, which is LaGranda's birthday.
They met in an alley after school. The girl brought Gutierrez and a woman who authorities believe is the girl's aunt. Authorities said all three assaulted the 12-year-old victim.
"At first she didn't care that she was hurting a little kid, she just wanted to defend her daughter," LaGranda said.
Police say LaGranda sustained a fractured wrist in the fight.
Gutierrez was arraigned Thursday afternoon. Her attorney declined to comment. Investigators are still looking for the aunt and Gutierrez's daughter.
If convicted, Gutierrez faces a possible maximum seven years in state prison.
LaGranda says the incident has taught her to make better choices about resolving conflicts in the future.
"I learned my lesson not to fight anymore," she said. "Violence is never the answer."