An explosion at the Mitsubishi Materials chemical plant in Yokkaichi, Japan on Thursday killed five people and injured at least 12.
The Mie Prefecture Police Department reported that the explosion occurred during a maintenance and cleaning operation at the chemical plant. According to Mitsubishi Materials, a heat exchanger exploded outside one of its facilities while it was being cleaned by approximately 20 workers and supervisors. The company speculated that the explosion could have been caused when a chemical agent inside the heat exchanger was exposed to air.