About 15 homes have been evacuated as more than 40 firefighters battle a mile-long mountain fire in Gwynedd.
North Wales Fire and Rescue Service said the gorse blaze at Mynydd Cilgwyn in Carmel was one of several fires the service was currently attending.
It said a village hall would be used as a rest centre for residents affected.
Some residents reported a number of homes were without electricity after wooden poles carrying power lines caught light.
Carmel resident Lisa Jones, who lives about 100 yards from where the blaze currently is, said she had "never seen a fire like this before".
"It's so sad seeing people having to flee their homes under such circumstances," she said.
She added she had not yet been evacuated from her home but fire chiefs were monitoring the situation.
NWFRS's senior fire safety manager Stuart Millington said the cause of the fire was unknown and once the blaze was under control a full investigation would begin.
The service said it was being "flooded with calls about fires in the open" as the summer heatwave continues.
Its crews are at fires in Talsarnau, Rhiw, Llanycil and Bangor Mountain in Gwynedd and Newborough Forest, Anglesey.
The service urged people to "take responsibility for their own actions" by using barbecues safely, extinguishing cigarettes properly, avoiding burning garden waste and keeping mirrors our of sunlight.
South Wales Fire and Rescue Service said its crews were at two fires - one in Kilvey Hill in St Thomas, Swansea, and another at Penrhys, Rhondda Cynon Taff.
Earlier a police helicopter was sent to a large forest fire near the Bryn Pica landfill site in Aberdare, Rhondda Cynon Taff, but fire crews have now left the scene.
A warning has been issued by Rhondda Cynon Taf Council that anyone found deliberately starting grass fires will face prosecution.
** RT PLEASE We're being flooded with calls about fires in the open - please be aware that our crews are already dealing with fires in Talsarnau, Newborogh Forest, Rhiw near Pwllheli, Bangor Mountain and Llynycil near Bala. Avoid repeat calls please. Thanks for your assistance— North Wales Fire (@NorthWalesFire) July 2, 2018
It comes as crews returned to the scene of another wildfire, in Ceredigion, after smoke was spotted.
Firefighters took a water tank to the scene near the Cwm Rheidol reservoir on Monday morning.
A helicopter was brought in to drop water on the mountainside over the weekend, alongside Mid and West Wales Fire and Rescue Service crews.
The wildfire has been burning on and off since Tuesday and is one of three across Wales in the past week.
Crews are also battling a gorse fire at Carmel, Gwynedd.
Over the weekend, a large wildfire which broke out in Rhondda Cynon Taff on Friday was put out.
The blaze on Maerdy mountain reignited on Saturday afternoon, despite initially being extinguished early on Saturday.
A helicopter was brought in to drop water on the fire, which covered about six hectares (14.8 acres) of the mountainside, alongside South Wales Fire and Rescue Service crews.
Crews returned to the scene on Monday morning, but no action was needed.
In Maesteg, Bridgend county, a fire on Garth Hill caused 92 people to call the fire service on Friday night.
The blaze, on six hectares (14.8 acres) of scrub and gorse, was out by early on Saturday.
A grass fire on Pembrey Mountain in Carmarthenshire, which started on Friday, was also put out in the early hours of Saturday.