Sonic boom heard over Washington DC sounded like explosion as jet fighters pursued plane before it crashed into mountain

A LARGE sonic boom heard near Washington D.C. was caused by a military flight pursuing another aircraft, officials say.

The noise was heard in the area just after 3pm on Sunday afternoon, prompting multiple 911 calls.

The Annapolis, Maryland Office of Emergency Management confirmed that it was, in fact, a sonic boom caused by an authorized Department of Defense flight.

Air National Guard F-16 jets were racing to catch a Cessna Citation aircraft that violated airspace in the Washington D.C. area when they caused the boom.

A source told ABC News that the Cessna was flying a strange path and revealed that the pilot had passed out.

The Cessna aircraft then "crashed into mountainous terrain in a sparsely populated area of southwest Virginia," according to the FAA.

That plane departed from Tennessee and was headed to Long Island, New York.

The FAA and NTSB will investigate that crash.

D.C. Homeland Security and Emergency Management were “aware of reports from communities throughout the National Capital Region of a loud ‘boom’ this afternoon. There is no threat at this time.”

Another source told ABC News that the White House and US Capitol were put on high alert.

Many concerned residents in the area called 911 and reported hearing an explosion.

"I live on the eastern shore of Maryland and it shook my house," one person tweeted.

Residents in Virginia also reported feeling the effects of the boom.

Others caught it on their home surveillance cameras and shared the footage on Twitter.