UPDATED: Orange County's Big Boom Sound Mystery Solved

Originally posted at 3:51 p.m. April 9, 2014. Updated with new details.

A loud boom today generated calls to emergency agencies in Orange County and authorities had trouble tracking down what caused it -- until the U.S. Navy confessed to being the culprit.

A U.S. Navy aircraft was conducting a supersonic flight that caused a sonic boom about 50 miles off the coast in an operation with the U.S.S. Ronald Reagan, according to Navy Lt. Reagan Lauritzen.

An earthquake was initially ruled out.

"We reached out to Caltech, and they said it's not seismic; it's sonic- related," said Vicki Osborn, an assistant emergency manager in the sheriff's department.

Officials at the Camp Pendleton Marine base were also mystified.

The base, south of the Orange County line, had no training scheduled or conducted today, Sgt. Christopher Duncan said.

"Right now we're calling around, seeing if any aviation assets maybe created some sound," Duncan said this afternoon.

An official at Edwards Air Force Base north of Lancaster was also unaware of any sonic events.

--City News Service