2) There are many members of Congress who are under scrutiny for various types of alleged malfeasance.
3) The Attorney General is particularly unapologetic about the raid, raising the possibility that more raids could come.
4) Friday was the last day before the start of a 3-day weekend, and the unofficial start of summer, and I am sure many people working in offices in Washington were thinking about their "getaways."
5) Then, a Congressman thinks he hears gunshots. People, at various times were locked in, then rushed out, then brought back, then rushed out, etc. Rather than describe the exact sequence of events, I think it is fair to say that the situation was chaotic.
6) Whether it was planned or not, this would present a unique opportunity for anyone with potentially incriminating or just embarrassing documents, files or other mater in his or her possession to remove, destroy, or otherwise dispose of it.
Now, I do not necessarily believe that this is a Republican plot (but it would not surprise me if Karl Rove cooked up something like this); this is the sort of thing that is very likely serendipitous, and the idea to do what I said in #6 above could have spontaneously occurred to a number of people at Rayburn.
I think it would be very interesting to see just how much more shredded paper is sitting in the recycling bins at the Rayburn building today as opposed to any other day after a weekend or three-day weekend.