Final answer:
The initial action taken by first responders upon arriving at an emergency scene, like a firefighter rescuing someone from a fire, is known as the primary assessment or scene assessment.
Step-by-step explanation:
The initial response done by the first responder to arrive at a scene, such as that of a firefighter entering a burning building to rescue individuals, is commonly referred to as the primary assessment or scene assessment. This critical action involves quickly assessing the situation to address immediate threats to life, prioritizing actions based on the severity of the incident, and ensuring the safety of the victims and the responders. First responders such as firefighters, police officers, and paramedics are trained to perform rapid, focused assessments to stabilize the situation and provide life-saving care.