The accident happened in the Seodaemun district during a safety inspection after workers detected a 2 centimetre subsidence in the structure and suspended construction operations. Fire officials said debris and concrete slabs suddenly gave way, crushing workers below. Images from the scene showed twisted steel beams hanging over damaged vehicles while police sealed off surrounding roads in the capital.
Officials from the Seoul Metropolitan Government said the inspection had started at 14:00 local time shortly before the collapse occurred. The overpass, built in 1966, had been under demolition since August 2025 because of safety concerns linked to its ageing structure.
Some debris also fell onto a nearby railway line, forcing the Korea Railroad Corp. to suspend part of its services to Seoul Station. Authorities opened an investigation into the cause of the collapse as rescue teams secured the unstable site and examined the remaining structure.