Readers reported around 3:15pm: “at Rock Creek Park and just heard very heavy boom in the distance almost like a sonic boom.”
“anyone else in Arlington (south of Clarendon) hear a massive boom about 10 minutes ago?”
From US Capitol Police: “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 U.S. Capitol Complex was briefly placed on an elevated alert until the airplane left the area.”