MANHATTAN - Muslim leaders gathered outside City Hall tonight, calling on Police Commissioner Raymond Kelly to resign after it came to light that the NYPD had been showing a movie about Muslim extremists during counterterrorism training sessions.The film called "The Third Jihad" contains images of Hezbollah rocket attacks and children being held hostage by Muslim militants. It was shown on a continuous loop while officers were signing in for counterterrorism training sessions from October through December of 2010. Records indicate that more than 1,500 officers and lieutenants may have seen it.Police Commissioner Kelly was featured in the video, talking about the danger of terrorists using nuclear weapons. Kelly and his communications director Paul Browne first denied the video's use in the training room, but later admitted to it. "Somebody exercised some terrible judgment," Mayor Michael Bloomberg said about the video, which is no longer in use. "I don't know who. We'll find out." The NYPD says the person responsible is a sergeant who has since been reprimanded. However, local Muslims demand that Kelly and Browne step down.