Fire crews from Bangor, Caernarfon and Llandudno are tackling a blaze on Bangor Mountain.
The fire was reported just after 3pm this afternoon.
A spokesperson for North Wales Fire and Rescue Service said: “We were called to a fire at 3.04pm on Saturday, 13 July.
“All three appliances are still on the scene, which has affected about 100 square metres.
“The cause of the fire is currently unknown as we are focused on trying to put it out.”
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Photos: Simon Murray