Police believe three empty school buses were set on fire on purpose on Monday night. They're investigating it as arson. Officials say the fire started just before 11 p.m. in the Robert's Hawaii bus yard on Old Fort Weaver Road. The fire damaged three buses, two are a total loss and the third has significant damage. The fire was brought under control at 10:58 p.m. and fully extinguished by 12:26 a.m. No one was injured. Damage is estimated at $200,000.