(Washington, DC)  --  The FBI is denying claims that an AR-15 was used in yesterday's Washington Navy Yard shooting.  Aaron Alexis was armed with three guns, a shotgun, and two pistols.  He was believed to also have had an assault rifle, but that appears not to be the case.  Three guns were found near his body.  Alexis had two prior arrests in previous shootings in 2004 and 2010, though he was never prosecuted in either case.