Fire officials say the blaze at 11 Madison Ave., near Madison Avenue Park in the Flatiron District on Saturday afternoon caused heavy smoke, but was quickly doused.
No injuries were reported and the cause of the fire has not yet been determined.
A 23-year-old teacher who was in the park waiting in line with friends at the burger restaurant Shake Shack said people at first started getting nervous but then everyone quickly calmed down once they realized there was no reason to panic.
Since late Wednesday, counterterrorism officials have been chasing a tip of a plot possibly timed to disrupt 9/11 events in New York and Washington.
