Los Angeles County firefighters and sheriff's deputies responded shortly after 11 a.m. to the campus at 21900 Centurion Way, near Bouquet Canyon Road, and an emergency helicopter was summoned to the scene.
After landing on one of the school's athletic fields, the chopper airlifted the patient to Northridge Hospital Medical Center in unknown condition.
"The student was conscious and speaking with medical personnel," a spokeswoman for the William S. Hart Union High School District told ABC7. "This was not the result of a stabbing."
Additional details about the medical emergency were not immediately provided.
A spokesperson for the L.A. County Sheriff's Department also confirmed that no stabbing or fight occurred.