Residents of New Jersey, New York, Pennsylvania and other E ast C oast states took to social media on Thursday asking, "What on Earth was that noise?"

A series of sonic booms were heard overhead, but officials at the Pentagon, U.S. Northern Command and the Coast Guard could not confirm the boom's origin.

"It was definitely not U.S. Air Force aircraft," an Air Force spokeswoman told Air Force Times.

Sources tell ABC News that the sonic boom was a result of the Navy conducting an F-35 test flight:

NEW: Sonic boom in NJ likely result of an F-35 being tested out of Naval test facility at Patuxent River, Maryland, defense officials say. — ABC News (@ABC) January 28, 2016

Did you hear that #SonicBoom in NJ? @USNavy saying it was an F-35 Joint Strike Fighter. Calm down people... it's just the sound of freedom. — Justin Fishel (@JustinFishelABC) January 28, 2016

But in the matter of public opinion the mystery continues, with many believing that agents Fox Mulder and Dana Scully from the X-Files should get on this mystery ASAP.

Here are some of the best Twitter and Facebook posts below:

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@QuakeAlarmMex @USGS When I was a kid back in the '60s, they were a common occurrence all over the country. Now, the sky is falling! 2 — Greg Durocher (@akrockhound) January 28, 2016