Firefighters are tackling a blaze at Ysgol Ein Harglwyddes in Bangor. The fire is in a detached classroom building.
North Wales Fire and Rescue Service were alerted to the incident at the school on Ffordd Caernarfon at just before 7.30 pm this evening.
Fire engines from Bangor and Menai Bridge are currently at the scene and are tackling the blaze which is believed to have spread to the roof.
At this time it is unclear as to how the fire began and an investigation into its cause will be undertaken.