The two were extinguishing a fire at Seoknan Pavilion, one of the scenic spots around the city's Gyeongpo Lake, before the pavilion collapsed around 4:29 a.m. They were pronounced dead after being rushed to hospitals.
About 10 minutes after the building collapsed, the firefighters, 59-year-old Lee Young-wook and 27-year-old Lee Ho-hyun, were rescued but were in cardiac arrest.
The fire at the pavilion started around 3:51 a.m. Another fire had broken out at the structure around 9:45 p.m. the previous day, but was extinguished in 10 minutes, firefighters said. The firefighting authorities placed it under surveillance with two firefighters and a fire engine on standby. The pavilion had caught fire again earlier Sunday after the firefighters and fire engine were gone.
Built in 1956 and maintained as a cultural property by the Hangneung municipality, the 10-meter-high wooden pavilion has a floor space of 40 square meters.
Police and firefighting authorities are investigating what caused the accident and looking into the possibility of arson.
"The two firefighters got into the accident as they obviously tried putting out the fire aggressively to save the cultural property," an official at the Gangwon provincial firefighting headquarters said. The authorities are also looking into a tip from residents that the construction of a hotel nearby caused the pavilion to crack in places.