U.S. Capitol Police (USCP) sent more than a few pulses racing on Wednesday when they evacuated the Capitol Building over a suspicious aircraft that they later cleared as a “no threat.”

“The USCP is tracking an aircraft that poses a probable threat to the Capitol Complex,” said the initial announcement that sent Twitter into a fury.

Minutes later, after the Capitol had been evacuated, police said there was “no threat” and the evacuation was only out of “an abundance of caution.”

Exactly what led to the cause for alarm remains to be seen, but all current indicators hint that a U.S. military aircraft had been conducting circuits near the Capitol.