yeah, this is stupid. In incidents like this there is a tendency to set up informal triage centres, i.e rather then having lots of injured poeple slumped on curbs and sign poles all over the place they all tend to gather or be carried to one or two locations that are A) sheltered B) provides a central (ish) location for the distribution of first aide and assistance and C) is an identifiable location to guide professional support to your location. The ambulance turns up there because thats where the injured people are.