Which of the following is a critical first action in managing a casualty in an unsafe environment?

Establishing scene safety is a crucial first action when managing a casualty in an unsafe environment because it ensures the safety of both the rescuer and the casualty. If the environment is unsafe, any attempt to provide care could result in further injury or loss of life to the person providing assistance or the casualty themselves. Before any treatment or assessment can effectively take place, the rescuer must identify and eliminate hazards to create a safe working environment.

By securing the area, the rescuer can confidently proceed with further assessments, like checking for responsiveness or calling for backup, without the immediate danger of injury from ongoing threats in the environment. This foundational step aligns with the principles of Tactical Combat Casualty Care, where prioritizing safety is paramount for both the caregiver and the casualty.