Washington, June 5 : US F-16 fighter jets while chasing an unresponsive aircraft that ultimately crashed in Virginia, caused a sonic boom across the Washington D.C. area, officials said. According to a statement issued on Sunday by the Continental US North American Aerospace Defense Command Region, the pilot of the civilian aircraft, a Cessna 560 Citation V, was unresponsive as the F-16 fighter jets attempted to make contact, reports CNN. It is typical for the Federal Aviation Administration (FAA) to call in jets if someone is flying unsafely. The F-16s were "authorised to travel at supersonic speeds", which resulted in the sonic boom heard in the Washington, D.C., area, the statement said, adding the fighter jets used flares "in an attempt to draw attention from the pilot". The Cessna was finally intercepted by the North American Aerospace Defense Command (NORAD) jets at around 3.20 p.m. on Sunday afternoon. "The pilot was unresponsive and the Cessna subsequently crashed near the George Washington National Forest, Virginia. NORAD attempted to establish contact with the pilot until the aircraft crashed," CNN quoted the statement as saying. Four people were on board the aircraft, which overshot its planned destination by 315 miles before crashing, according to informed sources. Search efforts were still underway by state and local authorities as of Sunday night, Virginia State Police told CNN. The National Transportation Safety Board said on Twitter it was investigating the crash. The agency said it will arrive at the scene on Monday and will begin "the process of documenting the scene and examining the aircraft". In a statement, the US Capitol Police said the Capitol Complex was placed on "an elevated alert" when the small aircraft flew near the area on Sunday afternoon,. "This afternoon, our officials were working closely with our federal partners to monitor an unresponsive pilot who was flying an airplane near the National Capital Region. The US Capitol Complex was briefly placed on an elevated alert until the airplane left the area," CNN reported citing the statement as saying. The US Secret Service said they did not alter their posture for keeping President Joe Biden secure after the incident. Biden, who was golfing at the Andrews Air Force Base golf course near Joint Base Andrews in Maryland, has been informed. /IANS