Widespread worry spread across the D.C. area Sunday afternoon when an aircraft flying into restricted airspace crashed in the D.C. area shortly after triggering a North American Aerospace Defense Command (NORAD) jet intercept accompanied by a thunderous boom.

Reports of a loud noise similar to that of an explosion poured into local law enforcement agencies and media outlets across the larger D.C. metro area on June 4 at around 3 p.m.

Several users on Twitter remarked that it had shaken their houses while local authorities scrambled to find the source of the noise and dispel residents’ worries.

NORAD released a statement later that day explaining that an F-16 fighter jet had been cleared to go supersonic to intercept a Cessna 560 that had flown into restricted airspace and was unresponsive.

Supersonic speeds travel faster than the speed of sound, or approximately 768 mph, creating a shock wave as the object pushes through air molecules at such a force that a shock wave is created, according to NASA. The release of this pressure results in a sonic boom.

Traveling from Joint Base Andrews, the F-16 pilot intercepted the wayward civil aircraft at approximately 3:20 p.m. but was unable to establish communication with its operator before it crashed near the George Washington National Forest in Virginia.

The Federation Aviation Administration (FAA) later released a statement that the Cessna aircraft had hailed from Elizabethton Municipal Airport in Elizabethton, Tennessee, and was bound for Long Island MacArthur Airport in New York, according to Fox 5.

An hour into the flight, the plane turned and headed toward D.C. for unknown reasons, according to The Washington Post.

The pilot Jeff Hefner was observed unconscious and slumped over in his seat by the F-16. An investigation is ongoing, with a team from the National Transportation Safety Board arriving at the crash site on June 5.

John Rumpel, the owner of the downed plane, told the WP that he had flown with Hefner for five years and had no problems with the Cessna, but another of his aircraft had recently been serviced for a pressurization issue.

Hefner and the three passengers — Rumpel’s daughter Adina Azarian, nearly 3-year-old granddaughter Aria, and a nanny who has yet to be publicly identified — were killed in the crash.

Rumpel, who had taken them to the airport earlier that day, was devastated by the news.

“That’s the end of my family,” said the 75-year-old, according to the WP. “It’s just my wife and I now.”