What Hit the Pentagon at 9:20am??????

Is this a simple mistake, or were there several events at the Pentagon (9:20am, 9:31am and 9:38am)?

WashPost:

At about 9:20 a.m., Lt. Col. Art Haubold, a public affairs officer with air force, was in his office on the opposite side of the complex when the plane struck.

"We were sitting there watching the reports on the World Trade Center. All of a sudden, the windows blew in," he said. "We could see a fireball out our window."

More on the timing of the Pentagon event here (scroll down to flight 77). There is very intriguing information in that article that needs serious study.