On Friday night, police called the Saskatoon Fire Department to the school, in the 200 block of Kenderdine Road, because witnesses reported seeing what appeared to be a ball of fire on the roof around 11 p.m.
Fire crews used their ladders to access the roof to search for the ball of fire, a fire department statement released on Saturday evening said, but found none.
Firefighters did find “discarded items” and traces of an accelerant that had previously been on fire, according to a statement from the fire department.
While attending, bystanders told the fire crews about a male youth with burns to his back and neck nearby.
Firefighters and paramedics attended to the burn victim before medics took him to hospital.
An investigator found no damage to the building but said there was reasonable evidence to suggest a fire was deliberately lit.
A police watch commander told Global News that three people, two 20-year-old men and a 15-year-old boy, have been charged.
The fire department wasn’t available for comment.