A Texas pilot flew a small plane into an Austin office complex today and authorities are investigating links to a hate-filled note found on the Internet, telling the IRS to "take my pound of flesh and sleep well."
Investigators are trying to determine whether Andrew Joseph Stack, the man identified by authorities as the pilot of the plane, is the same person as "Joe Stack," the name signed to the online rant that warns, "Desperate times call for desperate measures."
The office building complex where the plane crashed houses IRS offices employing about 190 people. The Austin Fire Department has concluded its search of the building and located the remains of two victims who have not yet officially been identified.
Police earlier said Stack died in the crash and two other people were taken to the hospital -- though later it was not clear whether or not those were the two people whose remains were found.
One of the injured was taken to the Brook Army Medical Center's burn unit. Referring to the missing person, Austin Police Chief Art Acevedo said, "The prospects are not very positive for this person at this time."
Watch "World News with Diane Sawyer" tonight at 6:30 ET for more on the pilot's suicide mission .
The online note appears to have a taken responsibility for the attack on the IRS in an anger-fueled rant that was posted online and was signed signed "Joe Stack (1956-2010)".
Federal officials investigating the note believe it have been written by Stack and consider it evidence, a sort of manifesto to help understand motive. The web page has been taken down at the request of federal authorities.
The note was titled "Well Mr. Big Brother IRS Man … take my pound of flesh and sleep well." It details years spent working and paying taxes, but not reaping the benefits of what he considered to be a functional government.
"I choose to not keep looking over my shoulder at 'big brother' while he strips my carcass, 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," the note reads.
"I can only hope that the numbers quickly get too big to be white washed and ignored that the American zombies wake up and revolt; it will take nothing less," he wrote.
While firefighters battled the huge blaze at the office complex, other firefighters were working to contain a fire at Stack's house, which he apparently touched off before heading for his plane.
The Federal Aviation Administration confirmed today that the plane, a Piper Cherokee, took off from Georgetown Municipal Airport around 9:40 a.m. The FAA said the pilot did not file a flight plan or communicate with air traffic controllers once in the air.
Department of Homeland Security officials were quick to say they did not believe the crash was an act of terrorism, but White House officials said both President Obama and Homeland Security Secretary Janet Napolitano were notified about the crash, and Norad launched two jet fighters to patrol over Austin as a precaution.
Eyewitnesses who saw the plane slam into the building said the pilot appeared to be in control of the plane in the moments before the crash.