The police are responsible for crime prevention, as well as the characteristics of maintaining public security work. They also need to have guns on duty. Therefore, they need to use guns to face the crisis situation. This case study found that after using a gun, the police had a great impact experience, including a traumatic response to a major stressful event, feeling shocked, sad, angry, regretful, self-blaming, helpless, and other emotional shocks, and getting helpless and anxiety with family members, stress on administrative responsibilities, pressure from media, and expects help from police organizations. Finally, this study proposes that in order to assist police organizations and police officers to face traumatic events and to resolve the damage and impact of trauma.