I saw the smoke from my office (on the 5th floor) which is some distance away from the crash site . . . thought it was a house fire or something.
Went down to the fitness center before lunch for a workout, turned on the TV to FOX, and saw it was a plane crash.
I drive by that building about every other weekend, so I'm somewhat familiar with the area. Local news reported that the building hit was one of three buildings in the "Echelon" office complex, and that IRS offices are in the building hit. Didn't know that . . . (FBI offices are in another building nearby.)
Local news reported that two people who work in the building are "unaccounted for." The plane came in over the Gateway Center shopping center (Container Store, Crate & Barrel, Whole Foods, Best Buy, couple of restaurants, etc.) across Hwy 183 so a lot of people saw it happen. Eyewitnesses said the plane appeared to be under control and going full speed as the plane dove into the building. One witness - a pilot - said the aircraft did "not seem to be in any distress."
Happened less than 2 hours ago, so news reports are still fragmentary and speculative. But some speculation has it that this MAY not have been an accident, but someone with a grudge against the IRS.