The youth has been suspended pending an administrative hearing on Monday. Lone Peak police also have referred the boy to the 4th District Court's juvenile justice system for possible charges.
"He claims he did not intend to burn the school down and was just playing with fire," Patten said.
While the rest room fire was quickly snuffed by a janitor, the stage fire forced an hour-long evacuation of an estimated 600 students. The children took refuge in a Mormon church building across the street from the school, which is located at 10326 N. 6800 West.
No injuries were reported.
"As far as damages go, there are no structural damages [from the fires]," Patten said. "The floor and walls of the stage, as well as the curtains, were not burned [and] the fire was contained in a small area on the stage floor.
"We feel fortunate that the fire was extinguished very soon after it was lit," he added.
Indeed, the stage fire, too, had been put out by custodial staff by the time firefighters arrived.
Firefighters ventilated the building, and students were returned to class by 9:15 a.m. Thursday.