Niagara police and EMS were called to the area of Main St. and Baker St. after reports of male in medical distress.
That was around 9:15 p.m last night.
Police say the male suffered a serious, but non life-threatening, injury after being assaulted with a weapon.
An investigation led to the arrest of female who can't be indentified under the Youth Criminal Justice Act.
She's been charged with aggravated assault and breach of recognizance.
Police say the victim and accused were known to each other.