Thee juveniles were charged with second-degree arson, breaking and entering, vandalism and conspiracy after they allegedly broke into the former middle school at 357 Park Place and set small fires in the bathrooms.
One juvenile was hurt when he jumped from a fire escape and was treated at Landmark Medical Center for an ankle injury. Police said they found him at the scene. Two other juveniles were seen running away.
The two others were arrested a short time later.
Police said they responded to the school after an alarm was triggered and the alarm company could hear voices inside the building.
Inside the building, police found several smoldering fires in bathroom areas and a discharged fire extinguisher in a separate area.