Speaking after the incident, a local firefighter gave more information.

Including the first victim and 21 missing people out of 22, we have recovered a total of 22 bodies and sent the bodies to hospital funeral homes.

We were going to wrap things up, but a factory official told us of one person who was unaccounted for.

We could not confirm whether the person was somewhere and couldn't be contacted or inside the factory.

The rescue workers are going back in to search for the person.

While South Korea's President Yoon Seok-yool also visited the site, Mr. Yoon inspected the area and spoke to authorities there, urging them to thoroughly investigate the cause of the blaze.

It appears to have started after batteries exploded while workers were examining and packaging them at the factory.

A reporter in Seoul, David Oh, told us that most of those killed were Chinese nationals.

As of 7 p.m. local time in South Korea, the authorities confirmed 22 people were confirmed dead.

And among those 22 people, most of them are foreign nationals.

Most of them are Chinese nationals.

I mean, initially the fire started at 10 in the morning and the fire brigade went to the place.

And initially the report was saying that there was one dead and 20 people are missing.

But it turned out that the massive fire has engulfed the entire factory.

I mean, not the factory itself, but it is a massive factory area.

And it started at the second floor of the three-story building.

And as you can see the pictures, the fire became a massive fire.

And in the afternoon, the fire brigades found more bodies.

And it turns out that there are more than 20 people are dead.

And at the moment, the fire has been almost extinguished, according to authorities.

But still, one people are missing.

Authorities are still looking for the missing.

We still don't know whether the person is inside the factory at the moment or outside of the factory, because they are just saying that he lost contact.

So, such operations are still ongoing in the area.

Well, let's speak now to Professor Paul Christensen, Professor of Pure and Applied Electrochemistry at Newcastle University here in the UK.

Paul, thank you very much for being with us.

We hear occasionally these stories about battery fires starting, many it seems, almost spontaneously.

Why are these batteries so dangerous?

I would first of all dispute that they're so dangerous.

But the great thing about lithium-ion batteries, and I am a fan, is that they store a huge amount of energy in a very small space.

But it's a double-edged sword.

The other side, what makes them hazardous, shall we say, is that they store a large amount of energy in a very small space.

And if that energy gets out in an is that, first of all, lithium-ion batteries do not commit suicide.

They are murdered.

In other words, it's down to the human factor, human error.

And it may not be anything to do with malpractice, just simply a lack of training, a lack of education.

And when they do go into thermal runways, they generate huge volumes of explosive and toxic gas.

And that's the problem.

So there's two parts to this then.

So first of all, how do they have to be handled to keep them safe?

Because, I mean, just in the studio alone, I'm probably surrounded by at least a dozen of them.

And when they do burst into flames, perhaps not spontaneously, how do they have to be put out?

How does that situation get treated?

You've got two very tricky questions there.

Now, first of all, lithium-ion batteries only go into thermal runaway, which is the problem, when they're abused.

Now, this can be through overcharging, overdischarging, crushing, penetration, or defects introduced at the manufacturing stage.

Now, when they go into thermal runaway, if you've got a small lithium-ion battery, drop it in a bucket of water.

But once you get to bigger ones, the cells, the components of the battery, are highly protected.

They're water.

And you do not need fire for the cells to go into thermal runaway one by one.

One cell can easily reach 600, 700, 900 degrees C.

And that's more than enough to trigger an adjacent cell into thermal runaway.

And when they vent the gas that's produced, as I've just said, if that gas is ignited immediately, you get blowtorch-like flames.

And that means that fire can spread very quickly indeed.

If the gases don't ignite immediately, you can get what's called a vapour cloud explosion.

There's a concern here, therefore, about how these batteries are transported and stored.

And most devices, I imagine, which contain these batteries are not made two miles down the road.

We're talking about them going on cargo ships and aeroplanes halfway around the world.

Is that part of the problem, that these things have to be transported so far?

I don't think so.

Because if you actually look at the number of incidents across the board, from e-scooters, which are killing people, by the way, to electric vehicles, to battery energy storage systems, to manufacturing plants, the number of instances or the percentage compared to the sheer number of batteries in this world is absolutely tiny.

Now, there are some hotspots, unusually, not manufacturing plants, actually, but more in recycling plants, lots of fires.

We've just had one in Paisley in Scotland.

E-scooters and e-bikes, I mean, there's a fire every single day in London due to an e-scooter or an e-bike or another light electric vehicle.

And those are what's killing people.

I mean, somewhere between 13 and 16 people have been killed in this country in the last few years by e-scooters and e-bikes.

It's not the transport.

But what we do lack are regulations and standards in this country, and that's a big problem because industry needs guidance, very much so.

Okay.

Professor Paul Christensen from the University of Newcastle.

Paul, thank you very much for joining us.