Last Updated Jul 22, 2014 5:55 PM EDT
NEW YORK -- Police are investigating after someone replaced two American flags on the Brooklyn Bridge with what appeared to be whitewashed or faded versions of Old Glory, CBS New York reported.
New York City Council member Mark Weprin tweeted a photo Tuesday morning:
The white flags - international symbols of surrender - fluttered Tuesday from poles on the stone supports that hold cables above the bridge connecting Brooklyn and Manhattan.
New York police Deputy Commissioner of Intelligence John Miller said police do not believe the incident was connected to any terror threat.
American flags fly from above the pillars year-round and are replaced by Department of Transportation workers when they become frayed, police said. They are lit from the bottom by a lamp at the base of each tower at night.
Miller said that as of around 8:30 p.m. Monday, the American flags were still flying on the Brooklyn and Manhattan towers of the bridge. But around 5:30 a.m. Tuesday, construction workers noticed the white flags had taken their place.
Surveillance video revealed that around 3:10 a.m., 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, Miller said.
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 two 20-foot by 11-foot flags on each tower, which appeared to be American flags with stars and stripes that had been bleached white.
Police also found large aluminum pans that had been affixed with zip-ties to cover up the lights that normally illuminate the flags.
The Emergency Services officers took down the rogue flags. Crowds gathered on the bridge and nearby sidewalks to watch as the officers climbed the cables to take them down from the towers.
Miller said the flag replacement operation appears 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.
Miller said police do not believe the white 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 police Commissioner Bill Bratton said the matter was serious nonetheless.
"Needless to say, no matter what the motive was, it is an issue of concern," Bratton said. "I'm not happy about it."
Miller emphasized that the white flag placement was not funny, and was not acceptable.
"We don't take these things lightly, or as a joke, or as art, or within the realm of speech," Miller said. "These are issues of trespass. They put themselves in danger. They put others in danger."
Miller said there has been no credible claim of responsibility and no indication of a message to be communicated with the white flags - whether one of patriotism or one of protest.
Whoever placed the white flags, once apprehended, will likely be charged with criminal trespass, malicious mischief and reckless endangerment, Miller said.
The Brooklyn Bridge is one of the most heavily secured landmarks in the city, constantly monitored by surveillance cameras.
More than 120,000 vehicles, 4,000 pedestrians and 3,100 bicyclists cross the bridge every day, according to the city's Department of Transportation, which maintains the span.