Transcript for Plane with unresponsive pilot crashes, killing all 4 aboard
ANDREW DYMBURT: This morning, some near the nation's capital are still rattled after a quiet Sunday was interrupted with this.
- It was very jarring.
- We thought it was probably an earthquake.
ANDREW DYMBURT: --a sonic boom startling residents across the region. This couple in Fairfax, Virginia, was recording a song when the boom causes them to leap out of their seat. The Capitol and White House were both briefly placed on high alert.
The sound was caused by 2 DC Air National Guard F-16s that were scrambled from Maryland, after a Cessna a business jet entered restricted airspace over the nation's capital. Around 3:00 PM, those F-16s going supersonic to catch up with the Cessna, creating a sonic boom heard in DC and surrounding areas.
The F-16s intercepting the plane using flares, in an attempt to draw the pilot's attention, but were unsuccessful. Ten minutes later, the plane crashing near George Washington National Forest in Virginia with four people on board.
- When the DC Air National Guard F-16s eventually caught up to this aircraft, they looked in the cockpit and they could see that the pilot was slumped over and unconscious.
ANDREW DYMBURT: Aviation experts say hypoxia may have incapacitated the pilot and those on board.
- The most likely scenario here is that there was some loss of pressurization, which induced hypoxia. Hypoxia is just the loss of consciousness due to lack of oxygen.
ANDREW DYMBURT: The incident bringing to mind the 1999 crash that killed champion golfer Payne Stewart and five others, after the pilots and passengers became unresponsive. That plane was flying from Orlando to Dallas, but crashed when it ran out of fuel over South Dakota.
WITNESS: It had been flying erratically. And within a matter of seconds, it corkscrewed and just went straight down.
ANDREW DYMBURT: Investigators concluded that the plane failed to pressurize and all on board were incapacitated due to hypoxia.
- It can make you feel lightheaded. It can make you feel euphoric. You may not even know that it's coming on until you lose consciousness.
ANDREW DYMBURT: As for Sunday's crash, the man who runs the Florida-based company that owns the jet, tells The Washington Post his daughter, and two-year-old granddaughter, her nanny, and the pilot were on the flight. He says they were returning home to Long Island, New York, after a visit to his North Carolina home.
Flight tracking data shows the plane made it to Long Island but didn't land. Instead, turning and heading straight to the DC area. Those F-16s were scrambled from Joint Base Andrews, where President Biden was playing golf with his brother at around the same time. Overnight, Virginia Police say they reached the crash site and found no survivors.
The FAA and National Transportation Safety Board will investigate what led to the crash of that Cessna.
This transcript has been automatically generated and may not be 100% accurate.