KYODO NEWS - Jul 26, 2018 - 21:51 | All, Japan

Five people died and around 40 were injured Thursday after a fire broke out at a construction site in suburban Tokyo and smoke engulfed workers.

One of the five died after failing to escape from the basement of the building that was under construction in the city of Tama. Of the injured, about 30 were in a serious condition, according to the Tokyo Fire Department.

About 320 workers were at the construction site of the seven-story structure, with three stories above ground and four underground. Insulation material seems to have caught fire after sparks were created when workers were cutting steel frames in the third basement level, police said.

The fire brigade, which received an emergency call at around 1:50 p.m., said about 5,000 square meters of the 17,500 square meters of total floor space of the building was damaged. The blaze was nearly extinguished about six hours later.

(Supplied photo)

Construction of the building started in October 2016 and was scheduled to finish this September, according to Hazama Ando Corp., the project general manager.

Workers who escaped from the site recalled how scared they were after being engulfed in black smoke.

A 20-year-old man working on the second floor of the building said he learned about the fire following a call from his boss. He ran 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 as the smoke blocked 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 of the fires, according to the fire department.

In Thursday's blaze, workers were using acetylene gas torches to cut steel frames, the police said, adding that sparks created during the work apparently set fire to nearby urethane material.

Urethane is often used as insulation material in homes and buildings.