Call it the Kincardine X-file.

A mysterious, explosion-like boom last Thursday evening that rattled this quiet town northwest of Toronto has yet to be explained.

The Kincardine newspaper reported that a meteor shower likely caused the thunderous bangs, which sent firefighters and Ontario Provincial Police looking for a problem they couldn't find.

Others pointed to a sonic boom from a jet, while some locals suspect the earth-shaking noise came from the neighbouring Bruce Power nuclear generating station.

"We can't confirm or deny anything. We have no explanation," said South Bruce OPP Staff Sgt. Paul Bradley.

Bob Mackenzie, who lives about 3 kilometres from the plant, said he was frightened when his house began to shake around 11 p.m.

"I was walking from my kitchen to my living room and there was this enormous noise, and the vibration came right up through my feet, like an earthquake," he said.

M.J. Stewart, another local resident, said the sound - two bangs about 15 seconds apart - was so loud that two picture frames fell off her wall. After the first boom, which shook her whole cottage, she went outside to investigate.

"It came from the direction of the nuclear power plant," Stewart said. "There were two very large steam releases over the plant. Even though it was night, the plant is so well lit you could actually see the big white cloud."

Company officials and the nuclear regulator maintain there is nothing to report from that night.

"It's a very interesting story, and I'm curious like any other resident, but it certainly had nothing to do with our operations," said Steve Cannon, a spokesperson for Bruce Power.

Sunni Locatelli, a spokesperson for the Canadian Nuclear Safety Commission, said regulatory staff at the Bruce site also reported nothing unusual. "There was no event at the Bruce site that would have led to those sounds," she said.

That leaves the meteor shower theory. Bradley said the London Emergency Dispatch centre did receive calls from people who said they saw large streaks through the sky at roughly the same time they heard a thunderous explosion.