NEW YORK (CBSNewYork) — A massive police presence surrounded the Brooklyn Bridge Wednesday – even with counterterrorism officers walking the beat – a day after unidentified vandals breached the security of the iconic span to replace the American flags with white flags.

As CBS 2 Political Reporter Marcia Kramer reported, the NYPD has blurry pictures of five persons of interest, amid concerns that terrorists will try to emulate the caper.

A police helicopter on Wednesday made repeated passes around the Brooklyn Bridge. NYPD radio cars patrolled the spans’ roadways, and police boats scoured the span from the water.

New security cameras were also installed, and numerous officers – some from the Intelligence Division and Counterterrorism Bureau – were assigned to foot patrols, walking back and forth between Manhattan and Brooklyn.

One counterterrorism officer who received the assignment said “no comment” when asked about it.

It all came a day after the American flags on the Manhattan and Brooklyn towers on the bridge were surreptitiously taken down, and replaced with white flags that appeared to be whitewashed or bleached versions of the American flag when viewed up close.

Surveillance video revealed that around 3:10 a.m. Tuesday, several people were seen crossing the bridge – four or five of them in a group. Several minutes later, the light that normally illuminates the American flag on the Brooklyn side of the bridge flickered and went out, NYPD Deputy Commissioner for Intelligence and Counterterrorism John Miller said in a Tuesday afternoon news conference.

About 12 minutes after that, the light on the Manhattan side of the bridge also went out, he said.

When members of the Emergency Service Unit went to the top of the bridge later in the morning to document the scene, they found the two new 20-foot by 11-foot flags on each tower. Police also found large aluminum pans that had been affixed with zip-ties to cover up the lights that normally illuminate the flags.

Emergency Services officers took down the rogue flags by 11 a.m. Tuesday.

Police said Wednesday that they have five unidentified persons of interest from a blurry video on the walkway around the suspected time the flags were replaced. They were described as white males in their late teens or early 20s, one of them carrying what appeared to be a skateboard.

The question for many was just how the group was able to evade the NYPD’s much-heralded security system.

“This is extremely embarrassing for the city as a whole – specifically the NYPD – that after hundreds of millions of dollars in resources, and the famous ring of steel that’s supposed to see all and know all, that five individuals – apparently just in the middle of the night – went up there, switched the flag over, and it wasn’t picked up for hours,” said security expert Manny Gomez.

Miller said Tuesday police do not believe the flags were intended to be a threat.

“It appears to have no particular connections to terrorism or even to politics,” Miller said. “This may be somebody’s art project or even a statement.”

But Gomez worried the incident showcases the city’s vulnerabilities, and could give al Qaeda terrorists the idea to copy the caper.

“It could have been a bomb; could have been a nuclear, biological, or chemical weapon,” Gomez said.

As CBS 2’s Alice Gainer reported, Gomez said if presumed amateurs could pull off the white flag stunt, terrorists could do far worse.

“If some kids could do this… what could seasoned terrorists — seasoned terrorists; trained terrorists with significant resources — do to this iconic landmark?”

Miller said Tuesday that the flag replacement operation appeared to have been pre-planned, since someone had to compromise a locked gate and know the size of the pan needed to cover the light.

He said someone with experience climbing in construction or bridge work also may have been involved, and the culprit may have scaled the bridge before.

The incident was a hot topic on the bridge walkway Wednesday.

“Where’s security? What happened?” said Manhattan resident Kat Melissa. “Are we really safe? Are we safe? What? What’s going on?”

“If you hang around, we’re going to put a British up flag shortly,” quipped British tourist Jim Waine.

Officials said police are looking for witnesses, and since no one has claimed responsibility, they are also trying to find out if the date was significant. It was 48 hours after the 45th anniversary of a man planting a flag on the moon in 1969.

No disciplinary action is expected against the officers on duty in the fixed-post patrol cars at the bridge entrances when the incident happened.

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