Firefighters work to put out fire at lithium battery maker Aricell's plant in Hwaseong, Gyeonggi Province. Korea Times photo by Choi Won-suk

About 20 bodies were found at the site of a lithium battery plant fire in Hwaseong, south of Seoul, on Monday, firefighters said, after the blaze had already left one worker dead and three others injured earlier in the day.

The deceased are believed to be among 23 people unaccounted for in the fire, they said, amid fears the death toll could rise further.

Of the 23 people missing in the fire, 20 are believed to be foreigners, including Chinese nationals, they said, adding the number is subject to change as the daily list of full and part-time workers was destroyed.

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 the main fire was under control as of 3 p.m.

Earlier, TV footage showed small explosions kept going off with showers of sparks in the burning plant.

Firefighters brought the blaze under control around 3:10 p.m., more than four hours after it started, and made their way into the plant and found the bodies.

A roof of lithium battery maker factory in Hwaseong, Gyeonggi Province is destroyed by fire. Korea Times photo by Choi Won-suk

Earlier in the day, the other deceased worker died after being taken to a hospital following cardiac arrest, while another was seriously injured and two sustained minor injuries, they said.

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 reportedly had 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 Fire Station that an explosive combustion occurred in one battery cell at the time of the fire.

Fire debris is shown in lithium battery maker factory in Hwaseong, Gyeonggi Province. Korea Times photo by Choi Won-suk

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.

The government convened an emergency meeting of the Central Disaster and Safety Countermeasure Headquarters in the afternoon to discuss measures to minimize casualties from the disaster.

Firefighters direct water at lithium battery maker Aricell's plant in Hwaseong, Gyeonggi Province, June 24. Yonhap

At the meeting, Minister of the Interior and Safety Lee Sang-min asked all relevant government agencies and local governments to mobilize all available resources and personnel to extinguish the fire and rescue survivors.

Earlier, President Yoon Suk Yeol instructed Minister Lee to make all possible efforts to search for and rescue the missing people by mobilizing all available manpower and equipment. (Yonhap)