A fire broke out at a building of South Korea's leading wireless and fixed-line services provider in central Seoul on Saturday, paralyzing the network in the region, fire authorities said, Yonhap reported.
The fire was fully extinguished after 10 hours, and no casualties have been reported.
The building of KT Corp., the country's No. 2 mobile carrier, located in the central Ahyeon district, caught fire around 11:12 a.m.
The authorities said the fire started in the basement of the building, where the company's communications equipment is located.
Firefighters extinguished most of the flames after about three hours but had to work several more hours to contain small flames as smoke kept rising. They mobilized excavators to dig up the ground.
The authorities said the fire was put out completely at about 9:26 p.m., about 10 hours after the first report was made.
"It was difficult to handle the situation because there was still heat inside and the underpass was long," a firefighting official said.
As a result, mobile and Internet networks, as well as Internet Protocol TV (IPTV) services, are down in mostly western Seoul and parts of Goyang, a city located just northwest of the capital city.
The operations of coffee shops, convenience stores and restaurants in the areas were also disrupted as the fire paralyzed their credit card payment systems that use KT's communications networks.
The authorities said it will likely take at least one week to fully normalize the system.
KT said it is looking into the exact cause of the fire and how much of the network has been affected.