The annex of a women-only spa facility in Tokyo's Shibuya Ward that was destroyed Tuesday in an explosion, killing three women and injuring eight people, was probably not equipped with a gas detector, police said Wednesday.
Sources said equipment to separate and release into the atmosphere methane that rises with hot water when the water is piped from 1,500 meters underground probably had not been checked since the spa opened in January 2006.
Police focused their investigation Wednesday on whether the methane may have become trapped inside the Shiespa building, causing the blast.