The Yankee Air Museum's 50,000-square-foot hangar, at Willow Run Airport near Ypsilanti, Mich., burned to the ground Saturday evening, destroying at least four airplanes and countless aviation artifacts. The crew of a B-25D who had just returned from a flight were able to save the airplane and the museum's two other flying classics -- a C-47 and a B-17G. The hangar, which is owned by the Wayne County Airport Authority, has been cited in the past for fire and structural safety concerns, according to the Detroit News. A 2001 report, commissioned by the museum, said the 63-year-old building lacked a fire-suppression system and proper fire exits. No one was hurt in the fire and the cause has not yet been determined. Museum President Jon Stevens told the Detroit News damage is estimated at between $5 million and $7 million. "Obviously, we had concerns with the old building," Stevens said. "We have been working over the last three years to raise money. At this time, we cannot do so." The hangar was originally built as part of a plant designed by Henry Ford to produce B-24 Liberator bombers on assembly lines for World War II. "It's a terrible loss, not only for us, who have put so much time and our hearts into that place, but really it's a loss for southeast Michigan and the aviation world," museum member Raymond Nickels told the News.