A software engineer furious with the Internal Revenue Service plowed his small plane into an office building housing nearly 200 federal tax employees after setting his home on fire Thursday, officials said.

Enlarge By Jay Janner, AP Smoke billows from a seven-story building after a small private plane crashed into the building Thursday in Austin. AUSTIN  As it dove out of the sky toward an IRS field office Thursday morning, Joseph Stack's small single-engine Piper Dakota became a screaming 3,000-pound missile. "It was low, straight and fast," said Stuart Newberg, who was stopped at a traffic light when Stack's plane whizzed past before slamming into the offices that housed 190 IRS employees. Stack, a 53-year-old software engineer apparently enraged over tax issues, plowed the plane into the side of the building, triggering a massive fireball that engulfed the offices. He is presumed dead, and one other person in the building is believed to have been killed; 13 others were injured, two critically. Emergency crews recovered two bodies. Austin Fire Department Battalion Chief Palmer Buck declined to discuss the identities of those found, but said authorities had now "accounted for everybody." The FBI said Stack is believed to have acted alone. But the plumes of black smoke triggered vivid memories of the 9/11 suicide hijackings that killed nearly 3,000 people in 2001, and renewed fears that even a small plane can cause horrific damage in the wrong hands. "It's a vulnerability, a weakness we hope terrorists don't exploit," said Rep. Michael McCaul, a Republican from Austin who is on the House Homeland Security Committee. A rambling letter that was part screed against the government and part suicide note appeared Thursday on a website registered to Stack. In the note, signed "Joe Stack (1956-2010)," he said he slowly came to the conclusion that "violence not only is the answer, it is the only answer." Three federal law enforcement sources, who spoke on condition of anonymity because the investigation is pending, said evidence authorities had gathered indicated that Stack had written the 3,000-word "manifesto." The writer of the letter complains that he is being unfairly targeted by the IRS and rages at accountants who prepared his taxes. "I choose to not keep looking over my shoulder at 'big brother' while he strips my carcass," the letter says. "I choose not to ignore what is going on all around me, I choose not to pretend that business as usual won't continue; I have just had enough." No warning at airport Stack, in recent years active as a bass guitarist with a honky-tonk Austin rock band, gave no indication that he was about to launch a deadly attack, according to many who knew him. Police said Thursday that something appeared to have set him off. Stack set fire to his family home Thursday morning, then headed to a small airport nearby. R.L. Quinn, owner of Awesome Aviation & Pilot Shop, said he saw Stack's distinctly painted plane around 9 a.m. yesterday morning as it left the area near his hangar. Quinn was driving a golf cart across the airport to drop off a letter. Aircraft normally have the right-of-way, but the pilot waited to let Quinn pass, he said. "I waved at him to say thank you," said Quinn, who knew Stack from seeing him occasionally around the airport. "He waved back." Twelve minutes later, the plane smashed into the Echelon I office building, near a busy highway intersection in northwest Austin and in sight of dozens of motorists. Austin Police Chief Art Acevedo credited a fast response by rescue workers with saving the lives of several people in the building. Acevedo also said the low-flying plane may have been spotted by some of the office workers in the moments before impact. "Some folks might have seen this aircraft coming and yelled out some warnings," Acevedo said. 'A reasonable guy' Billy Eli, 47, an Austin singer and songwriter, said Stack played bass in his band from about 2005-08 and that he gave no indication of being violent. Stack was part of the band, described on its website as "gritty Texan bar-room country," for an album called Amped Out. Stack appears on the album cover wearing a cowboy hat and jeans. Eli described Stack as "a reasonable guy who liked quality musical instruments. He wasn't a quiet guy, but he was not boisterous. A middle-of-the-road guy. He knew a lot of stuff about a lot of different things. He liked electronics." Eli said he last spoke with Stack just before Christmas. "Today was the first I knew he was having any IRS issues," Eli said. Jim Hemphill, 49, an Austin attorney who played guitar in the band, said he also was shocked. "I never saw anything like this in Joe," Hemphill said. "But we weren't the kind of friends who would talk about personal or political things. We just played music together." Hemphill said he saw Stack for the last time about a month ago when he had dinner at Stack's home, along with his wife and stepdaughter. The 33-paragraph manifesto that the FBI believes Stack wrote is typed neatly with near-perfect grammar. It drips with cynicism, paranoia and narcissism. In it, the writer rails on greedy corporations, corrupt politicians and, as an apparent last straw, a self-serving accountant who allegedly botched Stack's tax returns and got him in trouble with the IRS. California tax records seem to parallel the letter. Two of Stack's businesses were suspended by state authorities in California for tax problems. The state's Franchise Tax Board suspended the license of Software System Service in 2004 because of $1,153 in unpaid corporate income taxes from 1996 and 2002. Four years earlier, it suspended Prowess Engineering because the company failed to file a 1994 tax return, board spokeswoman Denise Azini said. Although the targets of Stack's apparent rage vary in his final letter, the gripe is consistent: No one cared about him. The manifesto begins with an indictment of politicians who are "not the least bit interested in me or anything I have to say," and goes on to say that he had discovered that his accountant "was representing himself and not me." Stack harks back to financiers in the Great Depression who leaped from Wall Street skyscrapers after losing everything. "Now," he wrote, "the poor get to die for the mistakes. "I saw it written once that the definition of insanity is repeating the same process over and over and expecting the outcome to suddenly be different," the letter says. "I am finally ready to stop this insanity. "Well, Mr. Big Brother IRS man, let's try something different; take my pound of flesh and sleep well." Small plane, big damage Even though Stack's plane — with a total weight of 3,000 pounds and a top speed of about 200 mph — is tiny compared with the large jets used by radical Islamic terrorists on Sept. 11, 2001, it was capable of creating a significant explosion and fire, according to aviation accident investigators. The Dakota carries up to 77 gallons of fuel, according to a Federal Aviation Administration (FAA) fact sheet on the plane. "That's enough for an enormous fire," said Steve Wallace, the former head of the FAA's accident investigation office. "And particularly if the pilot was deliberately trying to drive the plane into the building." McCaul, the area's congressman, agrees. "This little Piper caused devastating damage — it almost brought the entire building down," he said. McCaul added that he fears terrorists will see the damage Stack caused and plan copycat attacks. "I think it's been on the radar of al-Qaeda and others," he said of using private planes in terror attacks. "This just re-emphasizes the fact that it can be done, and they may attempt to do the same thing." When the Transportation Security Administration (TSA) proposed the first security regulations for private airplanes in late 2008, it exempted 150,000 small airplanes that it did not consider to be threats. The regulations, which are being revised, targeted 15,000 business jets that the TSA said could cause significant damage if terrorists were to pack one with explosives and fly it into a building. These jets "could be used effectively to commit a terrorist act," the TSA said in proposing background checks for people boarding private jets. That assertion was challenged last year by the Homeland Security Department's inspector general. Private aviation "does not present a serious homeland security vulnerability requiring TSA to increase regulatory oversight," Inspector General Richard Skinner said in a report. Homeland Security Secretary Janet Napolitano disputed the conclusion. Levin and Frank reported from Washington; Jayson from Austin. Contributing: Kevin Johnson in Vancouver, Brad Heath and Donna Leinwand in Washington. Guidelines: You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. Read more