A fire erupted early Sunday morning at a Posco factory in Pohang, North Gyeongsang Province, and was brought under control within hours. Yet, a series of incidents, including multiple fires at Posco’s steel plant, has heightened anxiety among local residents this year.

According to fire authorities, a fire erupted with multiple explosions at the Posco plant’s third Finex factory at around 4:20 a.m. Sunday.

After initiating an emergency response at around 4:50 a.m., deploying 43 fire trucks and around 120 firefighters, the fire was finally contained around 6:30 a.m., before being completely extinguished at 9:20 a.m. Firefighting efforts were challenging, not only because of the flames’ intensity, but also because the facility was 50 meters high, according to officials.

Unlike the traditional blast furnace process, Finex factories skip the pretreatment process of raw materials such as iron ore and bituminous coal to produce molten metal. Instead, the raw materials are placed straight into the furnace. While Finex factories are more time-efficient and cost-effective, they are more vulnerable to fires because they use pure or enriched oxygen, which makes the processing system more flammable and reactive.

Though the exact cause behind the fire is unknown, police and fire officials began their investigation on Sunday, believing that the fire was caused by rapid gas expansion in the air duct of the factory’s hydraulic room, leading to an explosion caused by fuel gas and a fire in the melting furnace.

Police officials added that the site of the fire had been preserved and that the National Forensic Service would conduct a forensic investigation to investigate the exact cause of the fire as early as Monday.

Based on the NFS’ forensics results, police and fire officials will also conduct an investigation to see if there were any anomalies to the factory’s equipment or worker negligence, and determine the scale of damage caused by the fire.

Of the eight workers inside the factory at the time of the fire, one was injured, while seven managed to evacuate safely. The injured worker suffered second-degree burns and was sent to the hospital.

Witnesses on site reported hearing “explosions that sounded like bombs” and earthquakes, as well as seeing “bright red flames” near the factory site with thick smoke soaring up into the air.

“My windows were shaking as if there was an earthquake,” a 68-year-old witness, identified by their last name, Seo, told Yonhap News Agency. “The smoke from the fire soon rushed into residential areas nearby, and I thought a war had broken out. Even though it was dark out, the smoke was visible to the naked eye.”

According to Gyeongbuk Fire Service Headquarters, several reports were filed on Sunday morning regarding the factory’s fire, with callers saying that they saw “large flames accompanied by multiple explosive sounds” and a “pillar of fire by the Posco factory.”

While the extent of the damage is yet to be determined, it is expected to take more than a week before the Posco plant can resume normal operations. However, according to Posco, no disruption in steel production is expected as the steelmaking company can respond by increasing the utilization rate of its blast furnaces.

“The blast furnaces are resilient enough to operate flexibly, so there is no problem with meeting the supply and demand,” said a Posco official. “The extent of property damage and the cause of the fire is still being investigated, but we believe that the damage to the facility is not significant, and we expect to be able to restart the plant’s operations soon.”

Posco has five facilities that produce steel, three of which are Finex factories and the other two being blast furnaces. Although the third Finex factory has been shut down due to the fire, the production of steel products will not be disrupted as the steel can also be produced through the remaining four facilities.

Fires have repeatedly broken out at the Pohang steel plant this year and in 2023. This January, a blaze ignited in the telecommunications line in the sintering area, but was extinguished within about 10 minutes. Another fire erupted at a coal transport facility in mid-February, followed by yet another on a raw material conveyor belt later that month.