To my mind, the mark of a good First Aider is the same as that of a triage nurse. You prioritize according to the severity, or potential danger, of each situation.
Panicking people fit into the latter category. But they had already calmed somewhat just by me turning up and taking control. I often joke that 90% of First Aid is crowd control, but it's all too often true.
The best way of doing that is to give people things to do. I sent the man to stand at the kerb and watch out for the ambulance. His job was to wave them towards the scene. He was perfectly calm once he was doing that.
I asked the woman to ensure that the gathering group of neighbors and passers-by didn't crowd us. She was great.
I was sitting with the boy, ensuring that he remained stationary, when his father arrived. I didn't want the boy to move, just in case there were spinal injuries that I couldn't see. He'd said that he had banged his head when he fell, but I couldn't feel any bumps.
Once Dad was there, my priority immediately switched to his asthma attack. His son had taken one look at him and apprised me of that condition! I reassured Dad that his son was fine, and tried to direct him to a nearby low wall, where we could sit down.
I'd just ascertained that he didn't have his medication on him, when the paramedics pulled up. I relayed to them his situation. One paramedic took over there, while I explained the secondary situation to the second paramedic.
When she walked over to the boy, I returned to my car and left. Job done.