Was it an explosion? An earthquake? A Klingon attack vessel?

Residents of Carroll, Douglas and Haralson counties, west of Atlanta, heard a big boom last night, and officials for all three counties spent considerable effort trying to figure out what caused it.

They're still trying.

Douglas County Communication Director Wes Tallon said "911 calls lit up" the switchboard after the 9:45 p.m. mystery noise rattled windows across a large area of west Georgia.

"There was no catastrophe, we know that," said Tallon early Saturday morning, who said the public did not report any fires or explosions.

And no utility companies reported trouble either. "We've called everyone under the sun trying to figure this one out," said Tallon. "We used the process of elimination and the only thing we can think of is that is was a sonic boom of some kind. To be able to be heard and felt 30 miles away in Haralson County it had to be something like that."

A sonic boom is a large shock wave created by an aircraft that exceeds the sound barrier, about 761 mph.

Tallon said he lives in East Douglas and did not hear the blast while watching football. But plenty of people did in the western area of the county and in Carroll and Haralson counties further to the west.

Villa Rica authorities dispatched several police and fire units to the Mirror Lake subdivision in the city, but found no damage or even smoke.

"People all over the city heard the boom, but we couldn't find anything," a police department receptionist said.