The exhibit was apparently part of a military appreciation night hosted by MLB’s Washington Nationals. Shortly after 6:25 p.m. ET, after dropping streamers to gauge the wind, a Golden Knights pilot gave an air traffic control tower at Ronald Reagan Washington National Airport his plan for dropping paratroopers, including figured out the specific direction they were planning to fly.
The United States Capitol police, apparently, had not been notified.
“Evacuate Now: Aircraft Intrusion” read the subject line of an email alert from Capitol Police issued shortly after 6:30 p.m.
“The USCP is tracking an aircraft that poses a probable threat to the Capitol complex,” the email began, listing instructions for people at various locations in the complex.
Capitol police moved quickly to evacuate the campus, setting off a piercing alarm throughout the Capitol and its surrounding office buildings. Officers were going door to door in the building to make sure those inside left as quickly as possible.
Outside, the sounds of sirens rang through the air as Capitol police chased staff members and curious tourists out of the area. Everyone was forced past the office buildings on both sides of Place du Capitole.
In the skies above, the plane in question could be seen making its slow circle around Washington as those eagerly awaiting answers pointed to the paratroopers falling into Nationals Park several blocks from South Capitol Street.
About 20 minutes later, Capitol police said there was no threat.
CNN has reached out to Capitol Police, Nationals, the military and the Federal Aviation Administration for comment.
In a statement, House Speaker Nancy Pelosi blamed the FAA for the incident.
“The Federal Aviation Administration’s apparent failure to notify Capitol Police of the pre-planned flyover of Nationals Stadium is outrageous and inexcusable,” the California Democrat said. “The unnecessary panic caused by this apparent negligence has been particularly damaging to members, staff and institutional workers still dealing with the trauma of the attack on their workplace on January 6.”
Reagan air traffic controllers, however, were aware of the Golden Knights flight, according to a liveatc.net recording.
At 6:21 p.m., an airport tower controller advised a Southwest Airlines flight that “two miles northeast of National’s tower is the Golden Knights plane,” and said that they were near the stadium.
The Southwest pilot replied that he had the plane in sight.
Such Capitol security alerts occur occasionally. The Capitol was briefly cleaned and the White House was temporarily locked down when a single-engine plane wandered into restricted airspace in April 2009.
It was also evacuated in January 2011 when a commercial airliner accidentally entered restricted airspace.
CNN’s Brian Rokus contributed to this report.