Fire fighters raced to the school on Hunter Drive at around 7.30pm.
A spokesman for the Scottish Fire and Rescue Service said: “We were called to an incident involving an external fire and Mearns Primary School at 7.31pm yesterday evening. Operation control mobilised four appliances to tackle the fire.”
School staff will be onsite this morning to assess the damage with East Renfrewshire Council posting on social media: “Following a fire at Mearns Primary School, education staff will be onsite again in the morning to assess any damage and update will be posted here”.
More to follow.