NORWAY – Several people in parts of Androscoggin and Oxford counties reported hearing an explosion-like noise early Thursday morning. The noise reported just before 9 a.m. may have been a sonic boom, officials said.

An Oxford County Communications Center dispatcher said several calls came in from Oxford and Hebron but a firetruck dispatched to Hebron Station Road was unable to determine the source of the noise.

Several people speculated it was a sonic boom from a military aircraft. A spokesman for the Brunswick Naval Air Station said he was unaware of any military training exercises in the area and that the noise was not created by aircraft from that base.

John James, public affairs director for the air station, said it’s “aerodynamically impossible” for any of its aircraft to go supersonic.

James, a retired naval aviator, said the culprit wasn’t from Brunswick. He said the sound barrier can vary depending on altitude and atmospheric conditions, but that the only military flights in the area that could break it would be Vermont Air National Guard F-16 fighter jets, which might be able to do low-level flights over northern Maine.

Aircraft from the Otis Air National Guard station on Cape Cod in Massachusetts also conduct occasional jet-fighter training in the region.