The blast occurred around 11:00 a.m. at the company’s research and development site, which works on advanced weapons technologies, rocket systems and aerospace projects.

Hanwha Aerospace CEO Son Jae-il said the accident may have occurred during the cleaning of equipment used in rocket propellant production, where explosive residue could have remained on tools.

The company pledged a comprehensive review of its safety procedures following the deadly incident. Political parties also announced they would scale back election campaign activities ahead of local elections as a mark of respect for the victims.

Fire officials said the blaze broke out around lunchtime, with many workers believed to have been inside the building, including a group gathered in a second-floor break room when the fire started.

Several people were injured after jumping from the building in an attempt to escape.

Search operations for the missing have been complicated by structural damage, with parts of the factory collapsing during the fire.

Authorities said phone data indicated the missing individuals were likely near the origin of the blaze.By around 6 p.m. local time, firefighters had contained roughly 80% of the fire, but rescue efforts were continuing amid concerns that casualties could rise.

The government of South Korea activated a centralized disaster management system following the incident, after President Lee Jae Myung ordered the mobilisation of all available resources to contain the fire and support rescue operations.

IThe factory is operated by Anjun Industrial, which manufactures engine valves and supplies major automakers including Hyundai Motor and Kia Corporation, according to information on the company’s website.

Company officials were not immediately available for comment.