The teen is a student at Dillard Middle School in Goldsboro.
Investigators said that on October 22, she made a threat by stating she planned to come "shoot up the school" the next day.
School leaders and Goldsboro Police were notified.
The school took action against the girl while the case was investigated.
In the meantime, investigators said the same girl made a second threat Sunday morning on social media.
The student was taken into custody and will be held at the New Hanover Juvenile Regional Detention Center in Wilmington, N.C.
She's facing two counts of felony communicating threats of mass violence on an educational property.