Smoke

The F-18 that crashed into a Virginia Beach apartment building produced a lot more smoke than whatever crashed into the Pentagon, while presumably carrying a lot less jet fuel.  Fuel seems to have sprayed over a large area.  I assume the explanation will be burning roofing.  

I can't get any more information from the pictures, as all I have seen are after the fire destroyed the evidence of the hole produced in the apartment building.  The earliest pictures all show a massive plume of very dark black smoke.  I'm still waiting for that perfect picture somewhere of a clean crash into a large reinforced building.