Someone has replaced two American flags on the Brooklyn Bridge with mysterious white flags.
They were fluttering Tuesday from poles that were perched on the stone supports that hold cables above the bridge.
Police said it was not clear what time they were placed there -- or by whom. The city's Department of Transportation had no immediate comment.
A parody Twitter account called @BicycleLobby joked on Tuesday that it hoisted the flags to signal "surrender of the Brooklyn Bridge bicycle path to pedestrians."
The bridge is one of the most heavily secured landmarks in New York, and is constantly monitored by surveillance cameras.
At least one of the flags, viewed via video, appeared to have faint traces of stars and stripes on it.
Several officers scaled the bridge and were seen lowering the flag on the Manhattan side around 11 a.m. ET as traffic inched along the bridge.
— By CNBC with AP