SOUTH KOREA – A toxic gas leak in the south Korea’s POSCO steel factory on Wednesday left 1 worker dead and 3 others experienced breathing difficulties according to local reports.

The incident occurred at a POSCO factory located about 270 kilometers (167 miles) southeast of the capital Seoul, where workers reportedly inhaled an unidentified gas while preparing for equipment repairs at one of the plant’s production lines, according to local police and the company.

Four workers were taken to hospital after experiencing breathing difficulties, but one worker in his 50s died while being transferred to the medical facility.

The remaining three workers were reported to be conscious and in stable condition.

Initial reports suggested that the leaked gas might have been hydrogen chloride fumes or nitric acid gas, but police and POSCO officials said further investigation is needed to determine the exact substance.

POSCO immediately halted operations in the affected area and ventilated the site before conducting safety inspections.

Police launched an investigation to determine the exact cause of the incident and whether adequate safety measures were in place at the time.