It was the boom heard round Staten Island.

An "explosion" rattled windows and nerves in homes from Huguenot to New Dorp last night, but the cause of the blast remained a mystery today.

About two dozen people called the Advance and dozens more posted on silive.com in search of an answer in what had become a guessing game late last night.

Police and firefighters responded to numerous 911 calls but came up empty.

What appears to be fact is that a loud "boom" at about 7:55 p.m. could be heard for miles.

But what was it?

Callers and posters to silive.com, the Advance's home on the Web, had their own ideas.

Which meant everything from a mortar to a meteor to a sonic boom, to an exploding meth lab to, as authorities believe, one heck of a king-sized firecracker.

"As of now we have no idea," said a police contact. "Nothing exploded in anyone's home or anything like that, and we checked all the power lines. ... We think it's probably fireworks."

The first of a flurry of 911 and other calls came from Clarke Avenue in Richmond and reported there had been a massive explosion in the neighborhood, followed by others who reported hearing the blast in Oakwood, Bay Terrace, New Dorp, Annadale, Eltingville and Huguenot.

The FDNY's Ladder Co. 85 in New Dorp was also dispatched but found nothing, and power company Consolidated Edison reported no outages or transformer explosions.

That didn't stop posters at silive.com, from weighing in fast and furiously.

"If this was heard and felt across this many areas it was NOT a firework. If it was, it was several blockbusters condensed/improvised," opined ITLBS1. "I would say possibly a transformer but I am sure people would have lost power if that was the case." After nearly four hours of speculation, the discussion had moved on to a possible sonic boom created by a spy plane.

The last sensory mystery around these parts took nearly four years to solve.

Last month, Mayor Michael Bloomberg announced that the city had pinpointed the source of a maple syrup smell that had occasionally wafted over the Island since 2005. The scent, Bloomberg said, was "the result of the manufacturing of fragrances and food flavors" in a New Jersey plant.

Phil Helsel is a news reporter for the Advance. He may be reached at helsel@siadvance.com.