Police arrived just before 830 to find two teachers and one student had been hurt by a machete-style knife and one man was arrested.
Three victims were sent to hospital and media reports have one teacher requiring surgery.
Fredericton police chief Leanne Fitch says if a student had not intervened and subdued the suspect a bad situation would have been a lot worse.
Fitch adds they believe its an isolated incident and they do not believe there is any additional threat to the community.
