Authorities are intensifying their investigation into Tuesday’s train accident in Cheongdo, North Gyeongsang Province, where two workers were killed and five others injured after being struck during a post-rainfall safety inspection.

Police said Wednesday that a 30-member special investigation team has been formed and a joint on-site inspection was conducted with safety investigators from the Ministry of Land, Infrastructure and Transport.

The investigation is focusing on whether safety protocols were properly followed, if the train engineer failed to see the workers on a curve with limited visibility due to vegetation, and whether emergency braking or warning signals were used.

Investigators have also secured the train’s black box, nearby CCTV footage, subcontracting records, and KORAIL’s safety inspection plans to determine if adequate worker protections were in place.

Prosecutors and the Ministry of Employment and Labor have launched parallel probes, including a special labor inspection into possible workplace safety violations.