WASHINGTON -- The U.S. Capitol was briefly evacuated Wednesday evening after police identified an aircraft that they said posed "a probable threat'' -- but the plane was actually carrying members of the U.S. Army Golden Knights, who then parachuted into the Washington Nationals' baseball stadium for a pregame demonstration.
The Nationals were hosting the Arizona Diamondbacks at Nationals Park, which is located a little more than a mile away from the U.S. Capitol.
The alert from the U.S. Capitol Police sent congressional staffers fleeing from the Capitol and legislative building around 6:30 p.m.
One witness to the chaos at the Capitol was Eireann Dolan, the wife of Nationals pitcher Sean Doolittle.
"I was walking the dogs past the Dirksen Senate Office Building," Dolan tweeted. ''People started streaming out all at once. They told me to turn around and get away as fast as possible. Some people were calm but many were genuinely panicked. I know I was."
Investigators were still working to determine why the event wasn't properly coordinated with law enforcement officials in Washington, two people familiar with the matter told The Associated Press. Multiple federal agencies began scrambling officials as the plane circled overhead.
The capital region is defended by several surface-to-air missile sites, as well as military aircrews on round-the-clock alert. It did not appear that any of those systems were scrambled.
Officials believe, based on a preliminary review, the pilot might not have properly reported taking off or had appropriate clearance, the people told The AP.
The Federal Aviation Administration said Thursday that it is reviewing the apparent communications breakdown with a "thorough and expeditious review."
The FAA said it "takes its role in protecting the national airspace seriously and will conduct a thorough and expeditious review of the events this evening and share updates." The agency said it knows its actions affect others, "especially in our nation's capital region, and we must communicate early and often with our law enforcement partners."
House Speaker Nancy Pelosi blamed the FAA in a statement Wednesday night, saying its "apparent failure to notify Capitol Police of the pre-planned flyover Nationals Stadium is outrageous and inexcusable.''
Pelosi said, "Congress looks forward to reviewing the results of a thorough after-action review that determines what precisely went wrong today and who at the Federal Aviation Administration will be held accountable for this outrageous and frightening mistake.''
Kelli LeGaspi, a spokeswoman for the U.S. Army Recruiting Command, which was behind the Golden Knights demonstration, released a statement saying, "We are reviewing all aspects of the event to ensure all procedures were followed appropriately to coordinate both the flight and the parachute demonstration.''
The aircraft, a twin-engine plane, took off from Joint Base Andrews in Maryland and had been circling inside heavily restricted airspace close to the Capitol when the alert was sent. Radar tracking data shows the plane, a De Havilland Twin Otter, remained clear of the prohibited airspace over the Capitol building and other government complexes at all times. Air traffic control recordings capture the Army plane coordinating its flight with the control tower at nearby Ronald Reagan Washington National Airport.
The plane landed back at Andrews around 6:50 p.m. after the parachutists descended into the middle of the field at Nationals Park.
Buildings on the Capitol complex were reopened a little after 8 p.m. The Diamondbacks won the game 11-2.