D.C. police said a woman called from inside a Navy Yard building to report that she might have heard sounds of gunshots around 7:20 a.m. However, investigators found no sign of a shooting, a shooter or anyone injured.
No arrests were made and no weapons found, officials said.
"At this time there is no evidence of gunshots," Mayor Muriel Bowser said. "There is no evidence of a shooter, and there is no evidence of any victims today."