The event took place Friday, Jan. 12, when the teen attacked a staff member with a weapon, said Hastings-on-Hudson Police Lt. David Dosin.
During the altercation, another student tried to intervene and suffered a "superficial" stab wound to the chest and a laceration to the hand, Dosin said.
The staff member received an injured lip, he added.
The 13-year-old, whose name wasn't released because of her age, was charged with two counts of felony assault and criminal possession of a weapon, Dosin said.
Her case will be handled in family court due to her age.
Graham Windham is a New York City-based nonprofit that runs residential treatment centers and schools throughout the area for children, youth, and families affected by abuse, neglect, and delinquency, with needed services.
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