The Roberts Police Department took the person into custody late Thursday afternoon and charges for several crimes are expected Friday, the newspaper reports.
Justin Walter Nelson, of Roberts, Wis., appeared Friday in St. Croix County District Court, where he was charged with arson, criminal damage to property and burglary, KSTP reported.
Classes at the school were cancelled for the remainder of the school year. Officials plan to have the students complete what's left of the school year at a nearby camp.
No one was injured in the blaze. Evidence at the scene indicates the fire was deliberately set, officials say. Roberts is about 40 miles east of the Twin Cities.