Firefighters were called to Thurso moors in the Highlands at 4pm and the blaze continues to rage.
Ron Gunn shared a shocking photograph of smoke above the town, which has a population of around 8,000 and is located on Scotland's north coast.
He wrote: "This looks a bit serious."
Crews from Thurso, Wick, Lybster and Dunbeath attended.
Resident Billy Gray captured video as work to extinguish the fire was under way.
He told Express.co.uk: "At about 4pm, I was heading upstairs and I have a window that looks over the Thurso moors.
"I saw lots of smoke and it just got worse.
"At 4.15pm, I called the fire brigade who were aware of the situation.
"I continued to spend most day upstairs monitoring what is going on as it was not far from my house.
"By about 9pm it looked well under control there were plenty appliances at the scene."