Five people died and around 40 were injured Thursday after a fire broke out at a three-story building under construction in Tama in western Tokyo and smoke engulfed the workers.
Four of the deceased were described Friday as men between the ages of 44 and 52 from Tokyo and Kanagawa Prefecture. The bodies of four of the five were found in the basement. The fifth was discovered on the third floor.
Of the injured, about 30 were in serious condition, according to the Tokyo Fire Department. In all, about 320 workers were at the site.
The fire brigade, which received an emergency call about the blaze at around 1:50 p.m., arrived to find smoke billowing out of the three-story structure, which also has four basement levels. The fire was extinguished about nine hours later.
The fire appears to have been caused by insulation material set alight by sparks from the cutting of steel frames in the third basement level, the police said.
On Friday, several dozen police officers and labor standards supervisors carried out an inspection of the building. Investigators said they suspect professional negligence was the cause of the fire.
Construction on the building began in October 2016 and was scheduled to finish this October, according to Hazama Ando Corp., general manager of the project.
According to the fire brigade, the building has 17,500 sq. meters of floor space and about 5,000 sq. meters were damaged by the blaze.
Workers who managed to escape recalled how scared they were after being engulfed by the black smoke.
A 20-year-old man who was working on the second floor said he learned about the fire through a call from his boss. He fled without knowing exactly where the exit was.
“I came across many dead ends. I’m glad that I survived,” he said.
A 26-year-old electrical engineer who escaped from the third basement level said he headed in the direction of voices because the smoke was blocking his view. Another worker, also 26, said he saw many people screaming “Help!” on the scaffolding around the building.
In Tokyo, around 100 to 200 fires occur at construction sites every year. Welding or melt-cutting work, cigarette butts and arson are often the cause, according to the fire department.
On Thursday, the workers were using acetylene gas torches to cut steel frames, the police said, adding that the sparks created by the cutting apparently ignited nearby urethane material. Urethane is often used as insulation in homes and buildings.