Police say the victim, also a female student, sustained irritation to the eye. But because the incident was near a stairwell, about a dozen other students claimed of exposure to the spray.
That prompted a hazardous materials scare, and the school was briefly evacuated.
The students were let back in an hour later.
The girl with the pepper spray was arrested and charged with assault and unlawful possession of noxious material.
Three students and a staff member were taken to a nearby hospital for irritation.
Ten others were treated at the scene.
None of the injuries were serious.
The two girls who were fighting both face school disciplinary action.
