Most of the posts so far seem to assume a 'simple' crash in the middle of an empty airfield, with the airframe sufficiently intact that the bodies/souls inside are whole bodies that can be counted, instead of a gruesome collection of parts.
How about a Citation carrying 5 P/SOB that comes down in an urban area. The fire crew search the wreckage and surrounding area and find 12 bodies. Is that all 5 from the aircraft plus 7 innocent bystanders? Or is it 7bystanders, 2 from the aircraft, with 3 still trapped inside? Or some other combination? My feeling is that the rescue services will continue to search the wreckage until they are convinced there is nobody left.
Looks like most of the posters are ATC or pilots arguing their own point of view. It would be very interesting to hear some ideas on the subject from professional firemen.