An investigation has been launched after fire ripped through a toilet block at Logans Primary School on Saturday night.
Emergency services were called to the building on Logans Road around 7.25pm.
The block, used by girls in P4-7, was well ablaze. Although the damage was mainly confined to the toilets, the repair bill is expected to run into thousands of pounds.
The school reopened as normal on Monday following the Easter break.
Councillor Jim Logue, convener of learning and leisure services, said: “We are outraged at this mindless act of vandalism to one of our schools and we are doing all we can to keep disruption to a minimum.
“We appeal for anyone with information to contact the police.”
It is believed the culprits gained entry through a smashed window, which was due to be repaired after being boarded up on Thursday.
PC Garry Cook, from the Safer Communities department, said: “These actions are completely unacceptable and will undoubtedly cause issues for the school. An investigation is ongoing.”
Information can be reported to police by calling 101.