A massive explosion at a chemical plant in Yeosu, South Jeolla Province, Thursday left seven workers dead and 13 injured.
The explosion took place at a high-density polyethylene plant in the city's industrial complex owned by Daelim Industrial at about 9 p.m.
There was a similar explosion that killed one person at the complex in 2003, and the cause of Thursday's incident is thought to be inadequate safety precautions. Police believe that lingering gas in a storage tank reacted with a flammable substance and exploded.
A fire broke out after the explosion but was contained in 10 minutes.
"Rather than the fire, it was the shock from the massive explosion that caused the high death toll," police said.
Many workers are severely burned, so the number of deaths will likely rise.