HWASEONG, South Korea, Feb. 26 (Yonhap) -- A total of seven people, including three officials of Samsung Electronics Co.'s chip plant, have been indicted on charges of professional negligence that led to last month's fatal hydrofluoric acid gas leak, police said Tuesday.

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 from one of the valves at the main semiconductor factory of the world's largest memory chip maker in Hwaseong, 60 kilometers south of Seoul, on Jan. 27.