Suicide Flight in Austin: what we know so far

In the wake of what are, after all, still only threats of anti-government violence from wannabe incipient fascists out there, I was stunned to hear of the suicide attack on the Internal Revenue Service in the beautiful city of Austin.  Ben Wear, at the Austin American-Statesman's news blog, reported that

The plane that crashed into a Northwest Austin office building today was a Piper Cherokee PA-28-236 Dakota, a discontinued single-engine plane first produced in 1977. According to risingup.com, an aviation Web site, the 236 Dakota has four seats, 235 horsepower and a top speed of 148 knots. That’s about 170 miles per hour. It carries a maximum of 72 gallons of fuel, weight about 3,000 fully loaded and has a range of 650 miles. The plane is just under 25 feet long and just over seven feet high.

The Associated Press, among other mainstream news agencies, have simply reported that Joseph Stack was angry with the IRS. I imagine that in the coming days we will hear liberal lefties claiming Stack was a teabag-like anti-IRS nut, while righties will emphasize the "class war" nature of his suicide note. The note, however, is, at least on my first reading, irreducible to leftist or rightist rant, but clearly angry at a government that props up the rich while soaking "the middle class." You can read the suicide note here. It concludes, in part: “Well, Mr. Big Brother IRS man, let’s try something different; take my pound of flesh and sleep well." --which, sorry for sounding insensitive, doesn't strike me as coherent politics in any sense. 
Market Watch felt it important to point out that it was an isolated incident. This was after F-16s were deployed over the crash site, surely a matter of routine, but one which must have been unnerving to an already shocked city. At the high end, it's estimated there were 190 employees in the building:  The GovExec blog reports that some media are saying one person is unaccounted for, while the IRS is saying all employees are accounted for--many of whom are receiving treatment for burns and smoke inhalation.