Your unit is first to observe a vehicle rollover with ejection. A second vehicle (a commercial bus) has an operator standing next to it. There are many victims in the remaining car, inverted, with several ejected. You communicate with Control to tell them that you need more resources. What are the critical communication points so far? How many patients? What conditions are life threats? Do some of these patients meet the criteria for airlift? Depending on the scene, what hazards are present to the rescuers? Can Incident Command quickly be established to dispatch additional help for you? This individual can relay patient status back to Medical Control to prepare facilities in the area for more substantial interventions.
In Mass Casualty, always evolving as we learn, there are many considerations. Communication and facilitation of resources on the scene are critical elements of Incident Management. There are many others.