HWASEONG, South Korea: Twenty-two people were killed in a massive fire at a South Korean lithium battery plant on Monday, most of them Chinese nationals, in one of the country’s worst factory disasters in years.

Over 100 people were working in the factory when workers heard a series of explosions from the second floor, where lithium-ion batteries were being inspected and packaged, firefighter Kim Jin-young told media.

In the massive blaze that ensued, 22 people were killed, including 20 foreign nationals — 18 Chinese, one from Laos, and one of unknown nationality, he said.

“Most of the bodies are badly burned so it will take some time to identify each one,” he said, adding that one person was still missing.

Initial investigations indicate that the fire spread in a matter of seconds, with toxic fumes quickly overwhelming workers in the area, said Cho Sun-ho head of the Gyeonggi fire department.

“White smoke began to rise from a battery part, and it took only about 15 seconds to cover the entire space due to the sudden ignition,” he said, adding that as it was a lithium fire, the workers’ efforts to extinguish wouldn’t have worked.

“It is presumed that the victims inhaled toxic fumes in a short time which would have suffocated them quickly, and made them lose consciousness,” he said.

Dozens of fire trucks were lined up outside the factory, an AFP reporter saw, with rescue workers carrying bodies, covered by blue blankets, out of the building on stretchers.

Wearing a green jacket which top officials don during emergencies, South Korea’s President Yoon Suk Yeol visited the disaster site late Monday, walking around the charred building in a hard hat and facemask before greeting firefighters at the scene.

Yoon said it appeared that “ignition material was positioned in front of the emergency exit, so workers could not escape and many people died.”

He ordered authorities to check similar factories that handle chemicals and take “measures to prevent such accidents from happening again.”

The vast factory had an estimated 35,000 battery cells on the second floor in storage, with more batteries stored in other areas, the fire department said. The bodies were found in that area.

Lithium batteries burn hot and fast, and are difficult to control with conventional fire extinguishing methods.

“Due to fears of additional explosions, it was difficult to enter,” the building initially, the fire department’s Kim said, describing the tricky rescue operation.

“As it is a lithium battery manufacturer, we (had) determined that spraying water will not extinguish the fire, so we (used) dry sand,” he added.

The lithium battery plant is owned by Aricell, a South Korean primary battery manufacturer. It is located in Hwaseong city, just south of the capital Seoul.

Shares of Aricell’s parent company, S-connect, plunged by over 20 percent on the Seoul exchange by close Monday. S-connect owns 96 percent of Aricell.

Lithium batteries are used in everything from laptops to electric vehicles — but can be highly explosive, with airlines, for example, imposing strict regulations on checking devices containing them.

Images shared by Yonhap after the fire broke out showed huge plumes of billowing grey smoke rising into the sky above the factory, with orange flames inside the building.

As the fire was blazing Monday, authorities in Hwaseong sent out a series of alerts to residents warning them to stay inside.

“There is a lot of smoke due to factory fires. Please pay attention to safety, such as refraining from going out,” one alert sent by text message said.

“Factory fire. Please detour to surrounding roads and nearby citizens please close windows,” another one read.

South Korea is a major producer of batteries, including those used in electric vehicles.

Its battery makers supply EV makers around the world, including Tesla.

The fire is one of South Korea’s worst factory disasters in years.

Previously, it’s worst chemical plant accident was in 1989 at the Lucky Chemical factory in Yeosu, Southern Jeolla Province, which resulted in 16 deaths and 17 injuries.

In 2011, three workers died in the explosion of oil mist at an HDC Hyundai EP plant in the southeastern city of Ulsan, while in 2012, eight people were killed after a chemical solvent drum can exploded at an LG Chem plant in the central city of Cheongju, Yonhap reported.