cops in Grand Army plaza

Anyone know what the police display this evening (August 16) was about? Dozens of cop cars came down Vanderbilt, closed off Grand Army plaza for about 5 minutes at around 10pm, and then left. Are the police trying out for the Rockettes?

lol... they do that in Manhattan allot. I think they are just "preparing” for an emergency/ terrorist attack.

Pretty amazing--I stopped counting at 40 police cruisers plus the main communications battlestar.