Introduction The incidence and severity of public mass shootings, and mass casualty incidents (MCI), continues to rise. Understanding the wounding pattern and incidence of potentially preventable death after these incidents is key not only to Health System and Trauma Center emergency response planning but also to community outreach and initial emergency interventions. Methods A retrospective study of autopsy reports after events with at least 10 fatalities exclusive of the assailants identified via the Federal Bureau of Investigation database from 1 January 1999 to 31 December 2020 was performed. Sites of injury, identification of weaponry, and identification of potentially survivable wounds were compiled. Results Nine events including 203 victims were reviewed. Overall, 56% of gunshots were to the head/neck/face; 37% were to the chest; 43% were to the abdomen/torso/back; 31% were to the lower extremity; and 36% were to the upper extremity. On average, there were 29 fatalities per event. Conclusion Emergency response disaster care strategy should focus on immediate point of care at the site of wounding by both the civilian population and medical personnel, as well as rapid extrication of victims for definitive medical care. Review of these autopsy results indicates exsanguination, often treatable, is the primary cause of death—supporting community education efforts in hemorrhage control. The location of the wounding patterns seen in this study warrants primary integration of craniomaxillofacial, orthopedic trauma, neurotrauma, and surgical critical care/trauma surgical specialists into the initial response team for MCI.