stack deliberately flew a single-emergency plane into an irs building in austin. it also appears stack set his own house on fire before taking off. it looks like he was on a suicide mission. stack and one other person in that building were killed. 13 others were injured. ed lavandera has more for us. >> reporter: here at the crash site in northwest austin, firefighters have returned to the scene going floor by floor, presumably to put out some of the hot spots of this fire that burned so intensity throughout most of the day on thursday. but the investigators continue their investigation. they are not saying much about what they have learned about joseph stack. most of what we've learned has come from friends and neighbors that knew stack and also from his rambling six-page posting what appeared to be a suicide note on a website registered in stack's name. in that note he talked about rambling on and on about his anger and frustration with the irs and the federal government as well. but federal authorities aren't