What actions should be taken first for scene safety and assessment during a BLS response?

The appropriate first action during a Basic Life Support (BLS) response is to check for responsiveness and activate the emergency response system. This step is critical because it ensures both the safety of the rescuer and the victim, while also making sure that professional medical help is on the way.

When checking for responsiveness, the rescuer needs to confirm whether the victim is conscious or unconscious. This provides essential information about the victim's condition and helps in deciding the subsequent steps. Activating the emergency response system promptly ensures that advanced medical assistance can arrive as soon as possible, which is vital for positive outcomes in critical situations.

The other options, while important in the BLS process, do not address immediate scene safety and the need for skilled intervention effectively. Starting CPR without checking for responsiveness may lead to unnecessary actions if the victim is responsive or breathing adequately. Calling for additional medical assistance before ensuring the scene is safe could expose the rescuer to danger. Lastly, only assessing the environment for hazards without taking immediate action to secure the scene and activate emergency services neglects the critical need for timely support in emergencies.