A fire broke out at a primary battery manufacturing plant, south of Seoul, on Monday, leaving at least one worker dead and three others injured, firefighters said. The blaze started at lithium battery maker Aricell's plant in Hwaseong, 45 kilometers south of Seoul, at around 10:30 a.m., they said, noting firefighting was still under way as of the early afternoon. The deceased worker was taken to a hospital after suffering cardiac arrest, while another was seriously injured and two sustained minor injuries, they said, adding at least 21 others are believed to be still stranded inside the plant. The fire reportedly occurred for unknown reasons at the three-story, reinforced concrete building with a total floor space of about 2,300 square meters. Firefighters are reportedly having difficulties completely putting out the blaze because burning lithium batteries are difficult to handle by conventional fire extinguishing methods. One witness, who escaped from the second floor of the plant, told the Hwaseong Fi re Station that an explosive combustion occurred in one battery cell at the time of the fire. The station said the fire spread rapidly as the battery cells inside exploded continuously, making it difficult for rescuers to go inside and search. At least 35,000 batteries are believed to be inside the plant. It said about 67 workers were on duty Monday, and there are 21 people who still remain out of contact, with fears there will be more casualties. Source: Yonhap News Agency