Families in about 20 properties have been evacuated from their homes as fire crews tackle a large mountain blaze.
North Wales Fire and Rescue Service said it had 30 firefighters at Blaenau Ffestiniog, Gwynedd.
One eyewitness said the hillside above the town looked “like a volcano”.
The alarm was raised just before 20:30 BST on Monday, with residents asked to leave the area in the early hours of Tuesday.
BBC Wales employee Laura Raymond said she was woken by firefighters “smashing open” fire hydrants at about 03:00.
“The hill was literally glowing from behind,” she said.
The blaze is thought to have started behind quarry workings in an area overlooking the town called Garreg Ddu – Black Rock.
“Black Rock is like a huge gigantic lump of coal, with burning embers,” said Ms Raymond.
“We’ve been well looked after and the crews have done an amazing job. We’re just so thankful because the crews have directed it away from the houses.”
Police have closed part of the Church Street through the town as fire crews continue to tackle the flames.
Teams from Dolgellau, Porthmadog, Blaenau, Harlech, Nefyn and Johnstown are at the scene, with an aerial platform called in from Bangor.
Many of the evacuated residents spent the night in a cafe, including Jackie Brunger.
She told BBC Radio Wales’ Good Morning Wales programme she was unaware of the blaze until fire crews arrived.
“It was just glowing orange and it was absolutely frightening – I’ve never seen anything like it. We were told to get away as soon as we could, so we took our car and went to the cafe.
“There was ash and bits of flame coming down. How far it has spread, so quickly – it was frightening.”