This incident highlights the dangers of frequenting old or abandoned buildings and the risks they pose as possible fire hazards.
Enquiries are ongoing to establish the full circumstances of the fire, however it is being treated as wilful.
Detective Chief Inspector Scott McCurdy said: “Fortunately no one was injured however it goes without saying that deliberately setting fires, whether in towns or the countryside, is reckless, irresponsible and can have serious consequences for the persons responsible, the wider public and emergency services responding to this type of incident.
“I would urge those responsible to think about their behaviour and what the outcome of their actions could be.
“While not all of these fires are started by young people, I would urge parents and guardians to make sure they know where their children are and to talk to them about the dangers of this type of activity.”
Anyone with information should contact 101, quoting incident 3133 of 21 September. Alternatively, information can be given anonymously through CrimeStoppers on 0800 555 111.