A friend of mine was in the Pentagon during the 911 attacks. He had a meeting discussing Army budgeting in General Maude's office. On the way to the meeting he stopped by an aides office who had the attacks on NYC playing on TV. He was so distracted that he forgot about his meeting with General Maude. His two aides went on without him.
Moments later the plane hit the Pentagon. The nose cone went right through General Maude's office window. They were, of course, killed instantly. The hallways started filling with smoke and since the building's E ring was recently renovated, many were unfamiliar with the exits which were purely marked. The communications were down as they had recently moved servers from the inner rings out to the E ring. Many people ran in the dark. The ones who ran down the wrong hallway died as they succumbed to the smoke. You had a 50/50 chance of getting out alive if you were in that part of the building.
The flames burned for hours. He said that it smelled like jet fuel. Think for a moment, if it were a missile, why would it continue to burn as if there were an accelerant? You have a reinforced concrete building and a "missile" and yet it took firefighters from all over to put out the flames which burned for hours. It was jet fuel because it was a plane.
Most of the people who were at the Pentagon that day just started walking. Thousands of people just left with no idea where they were going This made it even more difficult for the fire trucks to get in. Some of the trucks couldn't fit under a pipe bridge to get to the fire and so their ladders had to be cut off the trucks. Debris was on my friend's car as it was parked outside General Maude's office. He walked 9 miles home that day covered in soot and smoke.
RIP Timothy Maude. Gone but not forgotten.