A report of shots fired early Thursday at the same Washington Navy Yard where a gunman killed 12 people in 2013 prompted a massive police response and lockdown, but after an extensive search authorities issued an 'all clear' at the facility.

The facility where the shots were first reported was largely emptied Thursday as civilian and military law enforcement officers swept through, an official said. 

The building initially in question was the same one where a gunman killed a dozen workers in a rampage two years ago, according to a second source -- a federal official  who spoke on condition of anonymity for lack of authorization to publicly discuss details.

There was a swift and heavy police response that began blocks away from the sprawling facility, which is about a half mile from the U.S. Capitol. Reports of the shooting occurred after news that the FBI was establishing command centers around the country to monitor any potential terrorist threats around the July 4 weekend. 

"I am not aware of any specific threats," Navy Capt. Chuck Nash (Ret.) told Fox News.

In September 2013, military contractor Aaron Alexis killed 12 civilian workers at the Navy Yard's Building 197 before he was shot and killed by police. Some lawmakers have said Alexis fell through the cracks at the VA and should have been treated by mental health professionals, but they have stopped short of specifying what government doctors should have done differently.

The Navy Yard, in southeast Washington, is the country's oldest naval installation.

The Associated Press contributed to this report