Here's an incident that happened fairly recently right here in my town.
Link to news article.

The Flagler County Sheriffs Office on Tuesday filed charges of aggravated assault and the reckless display of a weapon, both felonies, against a 12-year-old Palm Coast girl who attends Rymfire Elementary school following an incident at a bus stop where the girl is accused of pulling a 12-inch knife and threatening a 10-year-old boy with it. Both the boy and the girl accused the other of teasing over a period of time leading up to Tuesdays alleged incident.
The girls parents were startled by the alleged incident, and when the father saw the size of the knife in question, he spontaneously exclaimed, Thats a sword.
The girl was not arrested, though she was read her Miranda rights and was detained for a period at the school, and the knife was entered into evidence. The charges were filed with the State Attorneys Office, which will decide whether to formalize them, reduce them or drop them. The girl was not allowed back in class. The district has a zero-tolerance policy against the carrying, displaying, and of course the use of any weapons, which generally results in suspension or expulsion. But the age of the alleged suspect may weigh in the districts decision on how to proceed.
Link to news article.