Fires broke out in multiple places at the country's top steelmaker POSCO in the southeastern city of Pohang on Tuesday.
According to the company, fires began simultaneously at two facilities within the plant at around 7:30 a.m.
Local residents said they heard a large noise and saw black smoke rising from the complex. The fires were visible from areas in the city's southern and northern districts, located far from the plant.
The company is trying to put out the fires while determining if they were caused by Typhoon Hinnamnor. There has been no confirmation on casualties or the extent of the damage.
On Monday, POSCO said that it planned to suspend production early Tuesday, including the operation of a blast furnace, as the typhoon was forecast to pass the region.