South Korea has declared a national emergency in response to one of the largest wildfires on record.
At least one person has died and more than 4,000 people have been evacuated.
Thousands of soldiers have been helping firefighters from across South Korea extinguish the flames in the country's north-eastern mountainous region, close to the border with North Korea.
Although the main fire has been brought under control, others are still burning, officials say.
It is believed the fire, which broke out late on Thursday, originated from a spark at a transformer near Goseong in Gangwon Province, north-east of Seoul.
Fanned by strong winds, it quickly spread through the mountain region which hosted the Winter Olympics last year, and to the cities of Sokcho and Gangneung, officials say.
More than 800 fire engines were brought in from across South Korea to help tackle the fire.
The blaze has destroyed several hundred buildings in the province.
President Moon Jae-in held an emergency meeting and called for officials to deploy all available resources.
Some 16,500 soldiers, 32 military helicopters and 26 military fire trucks have been deployed, the ministry of defence said.
"Fortunately, the main fire has been brought under control," provincial governor Choi Moon-soon said in a radio interview with news broadcaster YTN, but added that others were still burning.
The fire in the Sokcho region has been contained, the government said, while about 50% of the fire in the Gangneung region has been contained.
The last time a disaster of a similar scale hit South Korea was in 2007, when a crude oil carrier leaked thousands of tonnes of oil into the sea off the west coast.