Police are hunting two youths who climbed onto the roof of a school to deliberately start a fire and then watched from nearby as firefighters put out the blaze.
The fire caused “significant damage” to the roof and top floor of Woodfarm High School in Thornliebank, East Renfrewshire.
No-one was injured in the blaze, which started at around 10.30pm on Friday.
Police are appealing for information about the incident, which was captured on CCTV.
Detective Constable Stephen Walker of Govan CID, said: “The youths are seen on CCTV climbing up the side of the building and then onto the roof where they deliberately start a fire. They are then seen on Robslee Road, where they are joined by another male, watching the fire service attend to put out the blaze.
“Thankfully, no-one was injured in the fire.
“These youths have absolutely no regard for their own safety, nor the property or the cost or disruption their actions have caused.”