On the same day a man harboring a grudge against taxes flew his small plane into an IRS office building in Austin, Texas, another alleged terror threat that started in Denver fizzled out without any devastation. A United Airlines flight from Denver and bound for San Francisco was grounded in Salt Lake City after the pilots got hold of a threatening note, which was placed on the beverage cart shortly after the morning takeoff (via the Los Angeles Times). Initial reports implied a bomb scare, which isn't quite accurate, according to 7News. The pilots actually told the 168 passengers about the note as they announced their plans to land in Utah, and they apparently revealed its wording to some first-class customers once the plane had landed. Allan Braun, of Denver, tells The Salt Lake Tribune the approximate message was, "You will all die a second death." The FBI interviewed passengers and crew but didn't share further details on the note or its origin. The flight eventually landed in San Francisco at 8 p.m., which was 10 hours behind schedule. The Colorado Springs Gazette points out that the plane attack on the Texas IRS building, which killed at least two people and caused injuries, at least, to several others inside, wasn't the nation's first violent outburst against federal tax offices. In 1997 and 1999, a man broke windows, spilled gallons of gas, and then torched two separate IRS offices in Colorado Springs. The culprit was arrested in 2001.