An unseen, sweet-smelling cloud drifted through parts of Manhattan last night. Arturo Padilla walked through it and declared that it was awesome.

"It's like maple syrup. With Eggos. Or pancakes," he said. "It's pleasant."

The odor had followed Mr. Padilla and his friend along their walk in Lower Manhattan, from a dormitory on Fulton Street, to Pace University on Spruce Street, and back down again, to where they stood now, near a Dunkin' Donuts. Maybe it was from there, he said. But it wasn't.

Mr. Padilla was not alone. Reports of the syrupy cloud poured in from across Manhattan after 9 p.m. Some feared that it was something sinister.

There were so many calls that the city's Office of Emergency Management coordinated efforts with the Police and Fire Departments, the Coast Guard and the City Department of Environmental Protection to look into it.