Police are maintaining higher visibility in New York City two days after terrorist attacks in Paris killed at least 129 and injured hundreds more. The NYPD has upped its presence in crowded areas and around French government facilities since Friday, but department brass is emphasizing that there are no known threats to the city.

"This is a counter-terrorism overlay. This is a plan that we literally keep on the shelf," Deputy Commissioner of Intelligence and Counterterrorism John Miller told CBS This Morning. "In this attack, we immediately looked at it...we took the French government locations, but we also added in places that look like the targets, so, crowded places."

As CBS2 reports, the Giants-Patriots game this afternoon at MetLife Stadium will be subjected to greater-than-usual law enforcement scrutiny, both outside and inside the stadium. Meanwhile, members of the NYPD's Hercules Team—a heavily armed counter-terrorism unit—have been seen in Times Square, and police are ramping up constitutionally questionable bag searches, in subway stations and elsewhere.

"When you have a bunch of random places that you could find in any big city, that's a real challenge about how to spread resources," Miller said, referencing the fact that the Paris attacks were scattered between a stadium, a theater, and restaurants and bars. In light of that, security has also been stepped up at venues such as Webster Hall, where The Saddest Landscape will play tonight. The New York Times's Rachel Donadio compared Webster Hall to the Bataclan, the Paris venue where attackers killed dozens attending an Eagles of Death Metal show.

Fear of an attack here has pervaded some usually humdrum activities. As the New York Times reports, Times Square tour buses saw low sales yesterday, while a series of technical difficulties during Friday night's performance of Aladdin on Broadway caused some anxiety.

"It's a vulnerable position, being onstage in front of 1,800 people, not knowing if there’s one person who wishes someone harm," actor Khori Petinaud told the Times.

Speaking to ABC's 20/20 on Friday night, Mayor Bill de Blasio said the "if you see something, say something" approach is important.

"That phrase takes on a lot of meaning in the age of lone wolf attacks," de Blasio said. "And that means we have the chance potentially to stop them if our fellow citizens are able to report to the police things that they see."

Far from presenting the recent attacks as the work of "lone wolves," French President Francois Hollande described the coordinated shootings and bombings "an act of war that was committed by a terrorist army."