One of the men who reported that he had saw and heard explosions was Barry Jennings, who was trapped in Building 7:
Jennings was Deputy Director of Emergency Services Department for the New York City Housing Authority. On September 11th, 2001, he saw and heard explosions BEFORE the Twin Towers fell, while attempting to evacuate the WTC 7 Command Center with NYC Corporation Counsel Michael Hess.
Jennings also reported that, when he exited Building 7, the lobby was in ruins and they were stepping over dead bodies. The Official 911 report said that nobody was killed in Building 7. A lobby in ruins would indicate an explosion did occur within building 7