AUSTIN, Texas - A man apparently upset with the Internal Revenue Service set fire to his home, got into a small plane and crashed it Thursday into a multistory office building, authorities said.

At least two people were injured and a third was unaccounted for. The crash caused a fire and sent black smoke billowing from the seven-story Echelon Building.

Officials told The Associated Press that authorities were trying to determine if the pilot intentionally targeted nearby office space of the IRS. They spoke on condition of anonymity because the investigation was continuing.