YEOSU (Yonhap News) ― A gas leak accident occurred Thursday afternoon at a polysilicon factory based in Yeosu, a port city 455 kilometers south of Seoul, poisoning more than 40 workers, fire authorities said.

A total of 42 affected employees of Hankook Silicon Co. were taken to several nearby hospitals, with 41 of them experiencing bouts of nausea, the fire authorities said, but no casualties were reported.

The company had been conducting test operations after it built an additional factory in the area when a crack in the gas pipeline led to the toxic gas leak, the authorities suspect.

Hankook Silicon, established in 2008, is a producer of polysilicon, an essential raw material for solar cells.

The fire authorities and the company said they are currently looking into the exact cause of the accident.