According to first aid principles, what is a critical first step when encountering an emergency?

In emergency situations, assessing the scene for safety is crucial and serves as a critical first step. Before administering any first aid, it is essential to ensure that both the rescuer and the victims are safe from potential dangers. This includes evaluating for factors like traffic, fire, structural hazards, or hazardous substances. By taking the time to assess the environment, you help to prevent additional injuries to yourself or bystanders and can proceed with the necessary actions to assist those in need.

The other options, while important in the context of providing help, come after ensuring safety. Starting first aid without assessing the surroundings could put the rescuer at risk. Calling family members is not a priority during the immediate response, as they are not the first point of action. Performing a self-check, though helpful for personal safety, does not address the immediate needs of the situation. Thus, assessing the scene is the fundamental first step in effective emergency response.