Samsung (005930) is being investigated for allegedly covering up a gas leak at one of its South Korean factories that left one employee dead and four others injured. Yonhap News Agency reports that a 500 liter tank of hydrofluoric acid began leaking on Sunday at around 11:00 p.m. local time at a semiconductor plant in Hwaseong, South Korea. The incident escalated at 5:00 a.m. on Monday morning when the tank leaked for a second time. It is estimated that around 10 liters of acid escaped from the pipeline, mostly in gas form.

Samsung is said to have sent a maintenance crew to fix the problem, however it failed to report the incident to local authorities until after one member of the crew had died from prolonged exposure. Four other workers were hospitalized following the incident and were discharged shortly after.

“A small amount of diluted hydrofluoric acid leaked early Monday morning during maintenance at one of the gas and chemical supply systems at the Hwaseong site,” Samsung confirmed in a statement, adding that the situation has been contained and production was not affected by the incident.

A South Korean government official told AsiaE that Samsung is being investigated for not reporting the incident earlier. Investigators will also determine whether or not workers had access to proper safety equipment.