An explosion at a munitions factory sparked a fire that killed at least two people and injured five others.
The accident happened at the Hanwha factory in the central city of Daejeon at 4:17 p.m.
Two workers were killed, and five others were taken to a hospital, three of them seriously injured with burns all over their bodies and the two others with burns to their hands and faces, according to company officials and firefighters.
A total of 29 fire trucks and 55 firefighters were mobilized to put out the fire.
The impact from the explosion also damaged a door and a wall of the building, they added.
The officials said the explosion appears to have occurred while solid fuel was put into a rocket's propellant container.
"Some chemical substances exploded while the victims were recharging propellants," said a factory official. "It will take time before pinpointing the exact cause of the accident."
The deadly case does not involve any initial-stage products, the official said, while refusing to give further details as the factory is categorized as a military facility.
Hanwha's Daejeon factory is known as being involved in the development and production of guided weapons.