American flags replaced with white flags atop the Brooklyn bridge in New York

Police want to know who replaced two American flags on the Brooklyn bridge with white flags.

Authorities are not ruling out that it could be a possible act of terrorism.

Here you see officers taking down one of the flags Tuesday morning.

If you look closely, a hint of stars and strips can be seen on the flag -- suggesting it may have been whitewashed or a faded version of old glory.

A white flag is typically used as a symbol of surrender.

The Brooklyn bridge is under surveillance.

There is a police vehicle at each end of the bridge at all times.

And there are cameras, but none monitoring the top of the bridge.

Authorities are reviewing footage to see when the flags were replaced.