Spark from vapor likely ignited Bucheon factory fire that killed one firefighter, injured 7

A fire at a metal injection and printing factory in Bucheon, Gyeonggi Province, that left eight people dead or injured most likely started when a spark ignited flammable vapor produced during metal-cleaning work using thinner, investigators said Saturday.

A joint forensic team of about 20 officials from four agencies — the Gyeonggi Southern Police Agency, fire authorities, the National Forensic Service and the Korea Electrical Safety Corporation — began a combined on-site inspection at the factory in Naedong, Ojeong-gu, Bucheon, at around 9:30 a.m. Saturday.

The team focused its examination on the area around the third-floor thinner-cleaning workstation where the fire originated, and investigated how flames and thick black smoke spread so rapidly that two firefighters who had moved in for initial suppression were trapped before they could evacuate.

Police confirmed that metal-cleaning work using thinner was under way at the factory when the fire broke out.

Investigators believe the most likely cause was a spark — generated by static electricity, stray electrical current or friction heat — igniting hydrocarbon vapor produced as toluene in the thinner evaporated.

Despite conditions inside the cleaning workstation that were conducive to vapor buildup, no explosion-proof equipment or related safety installations were in place.

Dozens of thinner cans were also discovered within about one to two meters of the ignition point, some of them open.

Separately, hundreds of paint drums were stacked at the scene, which investigators believe contributed to the rapid spread of the fire.

The forensic team plans to send cleaning solution recovered from a workstation container to the National Forensic Service for detailed analysis.

Kim Hyo-seong, head of the Gyeonggi Southern Police Agency's forensic science unit, told reporters at a briefing that investigators considered it most likely that a spark from static electricity or friction heat ignited vapor while metal parts were being moved after cleaning. "The site appeared to have no explosion-proof equipment or facilities despite conditions that could produce flammable vapor," Kim said, adding that the exact cause would be confirmed through analysis of the recovered solution.

Police and fire authorities also plan to determine the precise composition and volume of flammable substances — including Class 2 petroleum products, a Category 4 hazardous material — found in large quantities at the scene, and to check whether the storage and handling of those materials violated regulations, including any unlicensed handling of hazardous substances.

The factory had no record of obtaining a permit for hazardous-material handling, and its floor area of 362 square meters fell below the threshold requiring sprinkler installation, meaning no sprinklers were fitted.

The fire broke out at around 8:38 a.m. Friday on the third floor of the five-story building and was fully extinguished at around 11:06 a.m., about two hours and 28 minutes later.

Two firefighters in their 40s who were among the first responders became trapped during suppression efforts; one was transported in cardiac arrest and later died during treatment, while the other sustained serious injuries. Four other firefighters and two factory workers were taken to hospital with heat exhaustion and smoke inhalation.