What are the first essential steps when arriving at the scene of a serious road traffic accident with injuries (Protocole PAS: Protéger - Alerter - Secourir)?

1. Protect the accident scene to prevent secondary crashes, alert emergency services (police/ambulance), and provide basic first aid without moving injured victims unnecessarily
2. Immediately move all unconscious victims into passing vehicles before signaling the scene
3. Give water and solid food to all injured victims before calling emergency services
4. Leave the scene immediately to avoid being questioned by authorities