Apparently someone was listening to an open, non-secure channel on a radio scanner about 10:00 a.m., when orders to shoot and the words “bang, bang” were heard over the radio channel. The words were being used to simulate shots fired during a routine, low level, low tempo training drill by the U.S. Coast Guard. The radio communications were likely heard on a radio scanner — a radios used to monitor police, fire and maritime communications by media, off-duty police and firefighters, and hobbyists.
Somehow the words were translated to news that actual shots were fired by the U.S. Coast Guard at a suspicious boating vessel on the Potomac River near the United States 9/11 Memorial Ceremony near Washington D.C.
The U.S. Coast Guard provided information about the training drill in a press conference at about 12:15 p.m. EDT. The incident occurred moments after President Barack Obama crossed Memorial Bridge on the river on his way from the Pentagon to mark the eighth anniversary of September 11.
False reports are explained by the U.S. Coast Guard to have spiraled up from the initial reports. The false news even caused departures from Reagan National Airport to be halted as a precaution at 10:08 a.m. Departures resumed at 10:30 a.m.