The lockdown and massive police response at the Washington Navy Yard Thursday morning was the result an employee who called police after believing she heard gunshots, Mayor Muriel Bowser told reporters.
"There is no evidence of gun shots. There is no evidence of a shooter. And there is no evidence of any victims today," Bowser said.
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Bowser added she is "very proud of all of the officials" who responded to the call.
The lockdown around the Navy Yard was removed around 11:30 a.m.
"We will review this event, what went right, what went wrong," said Vice Adm. Dixon Smith, commander of Navy Installations Command.
Workers stepping out of the Navy Yard Metro station Thursday morning were greeted by rows and rows of police cars, helicopters buzzing in the air, reports of a security lockdown and one or more active shooters heading through Building 197, a scene that immediately brought to mind the Sept. 16, 2013, shooting that left 12 dead and three injured.
Aaron Alexis, a former Navy reservist, opened fire around 8:20 a.m in the 2013 incident. The killings ended approximately an hour later when police shot him dead.
The 2013 shooting laid bare security problems at the installation, along with multiple communications problems among the National Capital Region's many local and federal law enforcement and military agencies.
This time around, the response "went very, very smoothly," said D.C. Police Chief Cathy Lanier. She added that the report came from a concerned citizen and does not appear to be a hoax.
The 2013 shooting was the second-deadliest to occur on a U.S. military base, behind the November 2009 Fort Hood shooting.