Aus 9/11 Wiki
´near the Lincoln Memorial´
"Somebody said the Pentagon's gone up," said Dave... Dave heard two booms, which sounded like the artillery salutes on the Mall on the Fourth of July, he said. It was likely the noise from a secondary blast at the Pentagon.
Second hand testimony from an anonymous ´witness´ quoting another anonymous ´witness´! Allegedly HEARD an explosion. Also heard the secondary explosion that is never discussed by the media.
Source List: SGYDK