Small plane crashes into Austin office building – was it intentional?

Witnesses say the single-engine plane appeared to accelerate before crashing into the seven-story building, where IRS employees, among others, worked.

A small airplane appears to have been intentionally crashed into a suburban Austin, Texas., office building that contains a local branch of the Internal Revenue Service, unnamed federal officials told the Associated Press.

Authorities in Austin sought to quell any concerns that the city was under attack or in any further danger, saying at a news briefing Thursday afternoon that the incident was contained.

"Categorically ... there is no cause for concern from a law-enforcement or a terrorism perspective," Austin Police Chief Chief Art Acevedo said at the briefing.

Authorities reported that so far two people had been taken to the hospital with injuries and that one person was unaccounted for. The building had not been completely extinguished even as the news briefing was under way, and officials said the search for any casualties would continue as first responders gained access to more of it.

Employees from several US government agencies – including the Internal Revenue Service – work there. Early news reports indicate that the man suspected of piloting the aircraft may have been targeting the IRS or, at least, the federal government.

One eyewitness reported that the aircraft was flying low above nearby apartment buildings about 10 a.m. Thursday local time before colliding with the building, sending a large fireball into the air. He told a local CBS reporter the plane was operating “smooth as could be” just before flying into the seven-story office building.

Other witnesses reported that the aircraft appeared to accelerate before hitting the building, which is about 15 miles from the nearest airfield.

The Federal Bureau of Investigation, which has a satellite office in a nearby building in the office complex, said Thursday morning that it was aiding in the investigation but that it was “too early to make any determination” on the nature of the crash.

But, according to the Austin Statesman, one Federal Aviation Administration official called the incident an apparent “criminal act.” If that is the case, the FBI would be part of the investigation.

CNN reported that federal officials said the pilot, who it identified as Joseph Andrew Stack, set his house on fire before flying to Austin. Mr. Stack, according to officials who spoke with CNN, took off from an airfield north of Austin without filing a flight plan with aviation officials.

The Austin Statesman uncovered online what appears to be a long letter from Mr. Stack. It begins: “If you’re reading this, you’re no doubt asking yourself, 'Why did this have to happen?' The simple truth is that it is complicated and has been coming for a long time.”

Chief Acevedo said reports that the plane was stolen were inaccurate and called the law enforcement efforts under way a "fluid investigation." He would not comment on the identity of the pilot or whether the crash was intentional.

Immediately after the crash, two F-16 jets from Ellington Field in Houston were scrambled as a precaution, a spokesman for NORAD (North American Aerospace Defense Command) told ABC News.

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