The gun scare was reported at the Gannett Building in McLean, Virginia. (Representational image)

The suburban Washington office complex housing the headquarters of USA Today newspaper was evacuated on Wednesday because of reports of a man with a weapon inside, but a search of the property found no threat or evidence of a crime, police said.

The gun scare at the Gannett Building in McLean, Virginia, coming amid frayed nerves following a string of deadly mass shootings, proved to be a "non-event," Fairfax County Police Chief Edwin Roessler Jr. told reporters.

The incident began around noon local time, Roessler said, when police received an emergency-911 call from someone in the twin-tower complex reporting that a former employee was in the building armed with a weapon.

That individual, who Roessler described as a "person of interest," was located elsewhere and was being interviewed by investigators, he said, adding there was so far no evidence the person in question had committed a crime.

"We cleared every single inch of that building, from the basement to the roof to the parking garages" without finding any sign of a threat, but it remained uncertain whether a gun had actually been present, he said. Police planned to examine surveillance video and question employees again to be sure.

The complex is home to USA Today, the newspaper's corporate parent Gannett Co Inc, and offices of other businesses. Roessler declined to specify where in the building the person had once worked. The precise origin of the 911 call was unclear, he said.

Asked about heightened anxieties stoked by a spate of mass shootings that killed a total of 35 people in Northern California, El Paso, Texas, and Dayton, Ohio between July 28 and Aug. 4, Roessler said workers in the Gannett Building responded correctly to a perceived threat.

"We need to look at this as a positive event," he said. "Everybody in that building did the right thing. They saw something that was out of place, and they called 911."

He added: "It shows that people in our county, and hopefully the country, are training themselves, both in the public and private sector, that if you see something, say something."

While public places of all kinds have been stricken by gun violence, news media have been targeted in attacks. Last year, four journalists and a sales associate at the Capital Gazette newspaper in Maryland were killed in a shooting and in 2015 two journalists were murdered during a live TV broadcast in Virginia.