An 89-year-old white supremacist is in a critical condition after a shoot-out which killed a security guard at the US Holocaust Memorial Museum. James W von Brunn walked into the Washington DC museum with a rifle and began firing indiscriminately, hitting one security guard. Two others returned fire, shooting the Holocaust denier in the head. The incident sparked terror in the heart of the capital's tourist area. Museum visitor Stephanie Geraghty, 28, said: "I heard the first shot. It sounded like something had been dropped from the upper stories down. The next two came really fast - bam bam. At that point everyone took off, chaos, running." The museum, which opened in 1993 and is a memorial to the 6 million Jews killed by the Nazis during the Holocaust, was packed with at least 2,000 visitors at the time, including many children. On his website, von Brunn - who was convicted in 1981 for an attack on a Federal Reserve building in DC and who wrote in a recent blog that Hitler's "worst mistake" was that "he didn't gas the Jews" - claims to have been a decorated PT-boat captain and lieutenant in the US Navy during World War II. Washington Mayor Adrian Fenty said: "I think this is an extremely isolated incident. In these days and times you never know when someone is going to grab a gun and use it in an inappropriate way as was done today."