A man has flown a small plane into the seven-story building housing the Internal Revenue Service, killing himself and one agency employee in an attack apparently over a tax dispute. “nvestigators are looking into whether the pilot, 53-year-old Andrew Joseph Stack, also set his house on fire before taking off in his single-engine Piper Dakota around 9:40 a.m. local time. Officials said they were evaluating an antigovernment manifesto posted on the Internet earlier Thursday, signed "Joe Stack," which suggested he planned the crash. "Violence not only is the answer, it is the only answer," the author wrote toward the end of a tirade against the IRS posted at 9:12 a.m. on a Web site registered to Mr. Stack. He described himself as a contract software engineer. By late Thursday night, emergency crews had found two bodies in the wreckage, the Associated Press reported. Authorities said earlier that the pilot who crashed into the building was presumed dead and that one worker in the building was missing. Thirteen people were injured, including two who remained hospitalized for critical injuries. More than 100 IRS employees work at the building.”