An explosion rocked a furnace in a plant manufacturing vehicle cylinder blocks. The fire that followed was brought under control by the firm’s internal emergency department; 3 employees were burned, one of who was severely burned on the face and back. Repercussions on the operation of the production line were feared. The operator had an expert assessment of the accident conducted. A cooling failure caused the explosion with a water-metal reduction reaction releasing hydrogen that exploded upon contact with the air