A fire likely sparked by exploding lithium batteries swept through a manufacturing factory near South Korea’s capital on Monday, killing 22 mostly Chinese migrant workers and injuring eight, officials said.

The fire began after batteries exploded while workers were examining and packaging them on the second floor of the factory in Hwaseong city, just south of Seoul, at around 10:30 a.m., fire officials said, citing a witness. They said they would investigate the cause of the blaze.

The dead included 18 Chinese, two South Koreans and one Laotian, local fire official Kim Jin-young told a televised briefing. He said the nationality of one of the dead couldn’t be immediately verified.

In the past few decades, many people from China, including ethnic Koreans, have migrated to South Korea to seek jobs. Like other foreign migrants from Southeast Asian nations, they often end up in factories or in physically demanding and low-paying jobs shunned by more affluent South Koreans.