NORWAY -- A loud boom that jolted western Mainers awake may have been a sonic boom from an aircraft, but an official says it wasn't caused by a plane from the Brunswick Naval Air Station.

People in parts of Androscoggin and Oxford counties say they heard the explosion-like noise Thursday morning just before 9.

An Oxford County police dispatcher says several calls came in from Oxford and Hebron, but there was no official determination of the source of the noise.

Spokesman John James of the Brunswick Naval Air Station says he's unaware of any military training exercises in the area. James also says the noise was not created by aircraft from that base because it's impossible for any of its aircraft to go supersonic.