Background Due to the deteriorating global security situation, many countries are preparing their health systems for armed conflict. Wartime health care delivery is challenging due to the loss of territorial control and attacks on Emergency Medical Services (EMS). The objectives of this study were to use Emergency Department (ED) data from the hospital closest to the areas of fighting during the October 7, 2023, attacks in Israel, to determine what patient factors relate to status as dead on arrival (DoA), high acuity, and to explore the epidemiology of injury patterns.Methods This is a retrospective cross-sectional cohort study. All patients presenting with injuries from the October 7, 2023, attacks, from 06h30 until 24h00, were included. Variables included demographics, patient classification (civilian or combatant), mode of arrival, condition, injury mechanism and injury location. Two logistic regression models with backward elimination were used to determine the patient factors associated with DoA and high acuity.Results A total of 301 patients were included. A majority (67.8%) arrived at the ED informally instead of by ambulance (23.9%). A total of 26.6% were DoA. Informal arrival was associated with DoA (OR 10.73, CI [4.18-36.55]). Injuries by firearms and thoracic injuries had higher odds of high acuity (OR 4.15 95% CI [1.67-11.50] and OR 4.35 95% CI [1.49-12.95]), while extremity injuries had lower odds (OR 0.41 95% CI [0.17-0.99]). Firearm-related injuries were more common among combatants compared to civilians (55.3% vs. 35.1%, p <= 0.05). Extremity injuries accounted for more than half of injuries in both civilians and combatants (52.3% vs. 59.5%, p = 0.31).Conclusion In an armed conflict with loss of territorial control and reduced EMS access, healthcare planners may need to anticipate significant prehospital death and that many patients arrive at hospital informally. Prehospital death may be reduced by expanding lay bystander skills in trauma care as these may access patients before ambulances do. Due to survival bias, patients with firearm-related injuries may have more urgent care needs upon reaching hospital than patients with explosion-related injuries. Given the higher survivability of extremity injuries, these may be overrepresented among patients who reach hospital.