Officers were called to the 100 block of Nelson Road at roughly 12:40 p.m.
A 16-year-old boy was said to be in possession of a hatchet, according to a press release.
Police said the school activated a perimeter lockdown and the teen was arrested nearby.
No injuries were reported.
The accused is facing charges of carrying a concealed weapon, possession of a dangerous weapon and mischief over $5,000, police said. His name cannot be released under the Youth Criminal Justice Act.