A lithium battery factory in South Korea was set on fire after multiple batteries exploded on Monday, killing 22 workers, most of them Chinese nationals, fire officials said.

The fire and a series of explosions ripped through the factory run by primary battery manufacturer Aricell in Hwaseong, an industrial cluster southwest of the capital Seoul.

The victims likely succumbed to extremely toxic gas within seconds of the blaze getting out of control, the officials said. It was unclear what caused the explosions and the fire was largely extinguished in about six hours.