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The 2010 Austin suicide attack occurred on February 18 , 2010 , when Andrew Joseph Stack III , flying his Piper Dakota , crashed into Building I of the Echelon office complex in Austin , Texas , United States , killing himself and Internal Revenue Service ( IRS ) manager Vernon Hunter .
 Austin, Austin , Texas, Internal Revenue Service, IRS
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Austin, Austin , Texas, Internal Revenue Service, IRS