Navy Yard Response Reflects Tensions, Worries About Attacks
 For two hours Thursday morning, it looked like the dire warnings of July 4th terror were coming true in Washington. 
 Police and ambulances swarmed the Washington 
Navy Yard after a worker said she might have heard gunshots. It turned 
out to be nothing, but authorities were quick to praise the woman for 
reporting possible trouble. 
 And law enforcement experts say it amounts to a 
dress rehearsal for the holiday weekend — a celebration of freedom that 
could be fraught with skittishness, especially in Washington. 
 "Any incident that you see in our nation's 
capital or you see in any major city across the country will frankly 
receive a similar response this weekend," said Clint Van Zandt, a former
 FBI profiler and an NBC News analyst. 
 American law enforcement is particularly 
concerned with the terrorist group's aggressive recruiting through 
social media and an ISIS spokesman's urging of supporters to attack during the holy month of Ramadan,
 which ends July 17. The symbolism of American Independence Day, and 
mass gatherings of people at fireworks displays in large cities as well 
as threat of violence specifically targeting police and military 
personnel, could be tempting, officials say.