Seven workers were taken to the hospital after a fire broke out on Monday at a South Korean plant of memory chip giant SK hynix, according to Yonhap news agency.

The fire occurred at around 10:32 a.m. local time (0132 GMT) in a sixth-floor gas room connecting two lines at the plant in Cheongju, about 110 km south of the capital Seoul.

The fire was immediately extinguished by the automated sprinkler system, but it triggered the leak of a highly toxic hydrogen fluoride, leading to the hospitalization of seven workers.

Among 10 workers at the scene, five reported eye irritations while the other two, who showed no specific symptoms, were hospitalized for medical checkups, an SK hynix official was quoted as saying.

The memory chip maker evacuated all of the about 3,600 employees at the lines as a precautionary measure.

The official was quoted as saying the employees will return once safety checks, such as air quality measurement, are completed, noting that there will be no production disruptions as facility operations were unaffected.