The stabbing happened around 10:45 am in the area of 9th and Baylor.
Sanger police say several men were involved in a fight at the school, which was out because of the holiday.
Officers say the 17-year-old sustained a stab wound to his upper body.
Sanger EMS arrived on scene and the juvenile was transported to a hospital in Fresno.
Sanger police say the neighborhood is typically quiet.
Police are looking for several suspects that are believed to be involved.
There are no leads at this time.
Police do believe this is an isolated incident and anyone with information is urged to contact the Sanger Police Department.
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