A destructive explosion at a lithium battery factory in South Korea caused a fire that killed at least 22 people, according to Reuters.

The factory is based in Hwaseong, an industrial hub 45km south-west of Seoul.

A search and rescue operation in and around the area is currently under way for five other people.

The fire began at 10.30am on Monday (24 June), and the firefighters brought it under control by around 3:10pm. About 100 workers were on-site at the time.

Firefighters took a prolonged amount of time to extinguish the blaze as burning lithium batteries are tricky to handle using conventional fire extinguishing methods, Yonhap News Agency reported. As lithium fire can be intensified by water, firefighters had to use dry sand to extinguish the blaze.

Kim Jin-young, a local fire official, told Reuters that the fire began after battery cells exploded inside a warehouse that held around 35,000 units. The cause of the explosion is yet unknown.

According to Yonhap News Agency, in addition to the unconfirmed number of deaths, at least one worker was seriously injured and two sustained minor injuries.

In response to the accident, the government held an emergency meeting at the Central Disaster and Safety Countermeasure Headquarters to discuss measures to minimise casualties.

Kim Jae-ho, fire and disaster prevention professor at Daejeon University, said the fire spread too quickly for workers to escape.

“Battery materials such as nickel are easily flammable. So often, there is not enough time to respond, compared to a fire caused by other materials,” he told Reuters.

If damaged or overheated, lithium batteries are at risk of exploding, and even after a fire has been put out, it remains at risk of reigniting without warning due to the chemical reaction already activated.