SEOUL • A fire swept through an apartment building under construction in the South Korean city of Sejong yesterday, leaving at least three dead and 37 others injured, the fire authorities said.

Fourteen Chinese workers were among the casualties, but it remains unclear whether any of the dead were Chinese, a spokesman from the National Fire Agency said.

Three of the injured were listed as being in a serious condition, he added.

The fire in the 24-storey building apparently started at 1.10pm in the underground parking garage, the spokesman told Agence France-Presse.

"There was a loud explosion and I saw huge flames and black clouds engulfing the building," an eyewitness told Yonhap news agency.

Another witness said: "Workers were shouting for help from windows and scaffoldings."

Construction firm officials estimated 169 workers were present at the site at the time of the fire.

About 40 fire trucks and 200 firefighters battled the blaze, but they were hampered by toxic gas and smoke from burning insulating materials, a firefighter at the scene told local media.

Firefighters faced difficulty battling the flames as there was no fire extinguishing system in the building, reported Yonhap.

A lot of flammable materials were inside the building, according to the fire authorities.