Police inspected a copper refinery Friday in Tamano, Okayama Prefecture, where five workers died and two others were seriously injured the previous day when they were buried by a brick wall that collapsed.
Police suspect company officials were negligent in ensuring the safety of the workers at the plant of copper refining company Hibi Kyodo Seiren, an affiliate of Mitsui Mining & Smelting Co.
The seven workers were buried around 10:30 a.m. Thursday when the inner brick wall of a copper converter they were working on collapsed. Ambulances were not called for five hours because other workers did not notice the accident and no foreman was present.