Severe skin and soft tissue infections (SSTIs) are often life-threatening emergencies that require a rapid diagnosis. Gas gangrene is one of the most fulminant types of SSTI and is usually caused by Clostridium perfringens' contamination of an open wound. Although gas gangrene is usually associated with fecally contaminated wounds, "spontaneous" cases occur and are most commonly caused by Clostridium (C.) septicum. We report a case of spontaneous gas gangrene caused by C. septicum that only became manifest while the patient was being monitored in the emergency department. We also review the diagnosis and treatment aspects of this entity.