mall they are preparing for all possibilities. new york city taking the greatest measures in years. hundreds of boaters will be watching the fireworks. spotters will be inside the crowds and 100 mobile cameras will capture the activities on land and in the air. >> there's no credible event to this event in new york city or elsewhere. our operating premise is we are the target in new york city all the time. >> reporter: on thursday within minutes of the first reported shots fired inside washington's naval yard the entire complex was locked down as hundreds of police s.w.a.t. teams and federal investigators swarmed the scene, blocking streets as helicopters hovered overhead. the threat a false alarm, but reveals law enforcement is at the ready this holiday weekend. >> bring your family have a