Fifteen houses have been evacuated as crews tackle a mile-long gorse fire on Mynydd Cilgwyn.
Around 40 firefighters have been called out to deal with the fire which broke out at just before 6pm on Monday evening.
Four people from evacuated properties in Carmel have been taken by Gwynedd County Council officers to a rest centre in the village. Others are staying with family and friends overnight.
Residents who have not been evacuated are being urged to stay safe and to keep their windows and doors closed. Police have also urged the public to stay away from the area.
North Wales Fire and Rescue Service say an incident command unit from Rhyl has been sent to the scene, along with crews from Caernarfon, Llanberis, Menai Bridge, Conwy, Llandudno and Porthmadog.
During the day, several gorse fires have been reported across the North West, including Bangor Mountain, Talsarnau, Newborogh Forest, Rhiw near Pwllheli, and Llynycil near Bala.
Four off-road units have also been called out and the National Police Air Service is helping crews with an aerial view of the gorse fire. A joint investigation with police and council chiefs into the cause of blaze will only begin once the fire has been brought under control.
Stuart Millington from North Wales Fire & Rescue Service, said: ”Although the cause of this fire is unknown, we are urging everybody to take extra care when they are out and about in grass and gorse land to help reduce the risk of fire – especially during the current spell of hot and dry weather.”
”During drier periods, fires involving grass, bracken and heather can develop very quickly, particularly in raised winds, resulting in fires getting out of control and spreading to neighbouring properties or forestry.”
”If you are out, make sure that any smoking materials are discarded and extinguished properly. If you are out camping, again make sure that campfires or barbeques are fully extinguished.”