The incident comes roughly three months after up to 10 liters of diluted hydrofluoric acid, a colorless acute poison that can damage the lungs and bones and even affect the nervous system, leaked at the same semiconductor plant in Hwaseong, 60 kilometers south of Seoul.
The world's largest memory chipmaker said that a small amount of hydrofluoric acid leaked around 11:30 a.m. Thursday when the workers were upgrading parts of an existing facility.
The injured workers were being treated for minor injuries at a nearby hospital, Samsung Electronics said.
"Only a small amount of hydrofluoric acid leaked," a Samsung Electronics official said.
In a statement, Samsung said it has reported the incident to the appropriate local authorities and is fully cooperating with investigations.
Meanwhile, the Ministry of Labor and Employment said Samsung Electronics has apparently not followed safety regulations, stoking concerns over the company's lax response to safety concerns.
The ministry said the toxic hydrofluoric acid leaked from the same gas pipes that employees were repairing on Jan. 28 when one worker was killed four others were injured.
Since January, Samsung has been under intense fire for not only failing to report the incident to the authorities promptly but also for the alleged cover-up.