Emergency services were called to Strathallan School, near Forgandenny, south of Perth, at around 7.20am yesterday.
The circumstances of the death are not known, but it is understood the youngster passed away at the scene.
A spokeswoman for the school said it was not able to confirm whether the teenager was a pupil at the school.
In a statement, it said it offered its “heartfelt condolences and support” to the family and all others affected.
A spokesman for Police Scotland said: “The death is being treated as unexplained. Inquiries are ongoing and a report will be submitted to the procurator fiscal.”