An annual skateboard race which had been due to run the length of Manhattan and draw up to 2,000 riders was banned by a New York judge.
The Broadway Bomb, as the event is known, started with a few dozen people in 2002 and last year saw 1,000 participants, riding colorful longboards down Broadway into New York's financial district.
The Broadway Bomb Facebook page showed just under 2,000 people signed up by Friday.
However, late Thursday, the New York State Supreme Court issued a restraining order to stop the race after the city complained that it causes traffic mayhem and danger both to riders and the public at large.
Organizer Ian Nichols posted on the Facebook page that "in order to avoid being prosecuted, Ian Nichols must officially cancel the Broadway Bomb and relinquish all responsibility."
However, in a defiant note, the message said "we are going to flash mob" and "start the race."