Mayor de Blasio: Brooklyn Bridge security breach a worry

BROOKLYN BRIDGE -- Mayor Bill de Blasio says last week's security breach at the Brooklyn Bridge is "a wake-up call."

De Blasio said Monday that the NYPD has increased security on all of New York City's bridges.

Police believe four or five people climbed the bridge's two towers on July 22 to replace the giant American flags with white ones.

The operation involved disabling a pair of spotlights and appears carefully planned.

The culprits remain at large and their motives are unknown.

PHOTOS OF THE FLAGS ON THE BRIDGE:

De Blasio, in his first comments about the incident, said he is "absolutely concerned" about a security failure at one of the city's most famous landmarks.

Some fear that next time a group with more sinister motives could penetrate the bridge's security.

De Blasio was in Italy during the incident.