At least two people were killed and four others were injured after a nitrogen leak at a plant operated by LG Display Co. in South Korea. Of the four staff and contractors who were injured by the leak, one was in a critical condition.

One of the workers died at the scene of the accident while another died while he was being taken to a hospital, Yonhap, the state-run news agency, reported. The leak occurred early Monday at the company’s factory in Paju, about 24 miles from Seoul, when the workers and the subcontractor were carrying out routine maintenance work. The nitrogen gas cylinder was open by mistake, causing the accident, the report said, citing firefighters. All the victims were reportedly in their thirties and were taken to four hospitals in the area.

"This is a terrible tragedy that the accident at the P8 factory left several casualties. The victims were exposed to a nitrogen leak during regular maintenance work at the eighth-generation line process facility. We are working to uncover the exact sequence of events," the company said, according to The Korea Times, a local newspaper, adding: "We will, to the best of our ability, help the victims recover from injuries and cooperate with authorities to reveals the cause of the accident. We also promise to work to prevent the recurrence of such an accident in the future."

Nitrogen is used to wash the display panels when they are being manufactured, The Korea Times reported. Although nitrogen is not a deadly gas, it can cause asphyxiation in the absence of oxygen.

The company said, according to The Associated Press, that it will cooperate with the authorities investigating the incident. Over a dozen firefighters also remained on location to make sure there was no further risk from another incident, Yonhap reported.

The incident follows last month’s accident at the Shingori 3 nuclear reactor in Ulsan, where a nitrogen leak killed three people.