A fire broke out in a warehouse in Kawasaki's Takatsu Ward on Saturday morning, gutting the two-story structure.
No one in the building was injured, although a 45-year-old woman who was watching the blaze fell from the second floor balcony of a nearby building, sustaining injuries to her head and arms, local police said.
According to police, the fire broke out at around 10:10 a.m. At the time, work was going on to tear down the building and investigators said they suspect that sparks from welders' torches set fire to debris nearby.
The firm that used to own the warehouse said the land and property had already been sold and a condominium was to be built on the site.
The blaze and accompanying black smoke forced students at municipal Takatsu High School nearby to remain indoors until the fire was extinguished.