(NECN) - New York Mayor Michael Bloomberg called the threat credible, but stresses that it has not been corroborated.
He said additional steps are being taken to keep the city safe, and there is no reason for anyone to change their plans.
He says New York has the best police department in the world and has kept the state safe over the past 10 years.
He said if you see something, say something. Go about your business as you normally would, just be vigilant.
Bloomberg also said the best thing you can do is to not be intimidated.
Call 311 if you see something suspicious and call 911 if you see something dangerous.