Multiple explosions occurred when five workers were acting on a footbridge structure at the top of crude olive pomace oil tanks. Welding on the tank roofs was performed without previously cleaning the tanks stopping their operation. First, one of the several approximate to 650-m3 reservoirs exploded, provoking a pool fire that spread throughout the tank farm. Roughly 1h later, two other reservoirs exploded causing the launching of missiles to a distance of 60-80m and a huge fire that extended throughout the entire tank farm. Four workers were killed instantaneously. The explosion was caused by the unusually high content of hexane in the crude olive pomace oil and, hence, by the inefficiency of the desolventization process which creates a flammable and explosive oil from a combustible one.