Soldiers guard at the Navy Barracks in Washington, Thursday, July 2, 2015. [Photo/IC]

WASHINGTON -- No injuries were reported at the US Navy Yard in Washington on Thursday, a spokesman for the Washington D.C. Fire Department said, after the facility was placed on lockdown following reports of a possible shooter.

A shooter had not been found as police swarmed the Navy Yard, according to a local CBS radio station, amid heightened security concerns ahead of the US July Fourth holiday weekend.

No further details were available about the incident at the Navy Yard, which is a mile south of the US Capitol and 3 miles from the White House.

The Navy said the facility was on lockdown but could not confirm any incident.

There were no injuries or victims, the fire department spokesman said.

A caller told authorities that shots were heard in Building 197, according to multiple reports, the same one that was the scene of the 2013 killings by Aaron Alexis, a former sailor who was working for a government technology contractor at the Navy Yard.

Lieutenant Commander Scott Williams, 39, a guided missile engineer at the Navy Yard, was in the building on Thursday and the day of the 2013 shooting.

He told Reuters that police came to his office at about 7:30 a.m. EDT (1130 GMT) and escorted him and colleagues out.