The investigation site was closed to the public, but the scene was bustling with investigators on Monday afternoon. Inspectors from the National Forensic Service also entered the underground hole in front of the KT building with special equipment. 

The fire, which broke out in the basement of the building on Saturday morning, is estimated to have caused 8 billion won ($7 million) in property damage.

No casualties have been reported, but millions of KT users in western Seoul were affected by a sudden network blackout over the weekend as the fire hit communications equipment that was installed in the basement.

During the first site investigation, which was conducted Sunday and took about four hours, the investigators found that 79 meters of underground cable had burned in the fire. However, the exact place where the fire broke out has not yet been identified.

 “Detailed plans for the (police) investigation will be determined after the second on-site probe,” Lee Joo-min, commissioner of the Seoul Metropolitan Police Agency, told reporters Monday.

Asked about the possibility of arson, Lee said it was unlikely as the doors to the underground tunnels are usually locked. But he added that the authorities would thoroughly examine KT’s underground facilities.

In addition to the on-site investigation, the Ministry of Science and ICT said it planned to inspect all telecommunication facilities, including 835 facilities that fall into category D, meaning that the responsibility for examining them lies with mobile carriers and internet operators.

The Seoul Metropolitan Government will also examine underground utility tunnels in the city to prevent any future network failure, the city said.

By Park Ju-young (jupark@heraldcorp.com)