The federal government is advising private property owners to raise their own alert level following the death of Osama bin Laden.
The Department of Homeland Security advised management companies and businesses that a terrorist threat could come in the form of an individual acting as a "lone wolf," the Washington Business Journal reported.
DHS sent messages to property owners on Sunday evening.
"In plain speak, it said they are encouraging increased awareness and vigilance, but are not aware of any current threat streams," Peggy Jeffers, of the Apartment and Office Building Association of Metropolitan Washington Inc., told WBJ.
"What you have to be looking out for is the radicalized individual," she said. "It's the coming months, not days for an organized al Qaeda response."
Across Washington, government agencies stepped up readiness, even though there was no known threat of attack.
D.C. police chief Cathy Lanier said on Monday, "Because we operate in undoubtedly the most important city in the world, the Metropolitan Police Department maintains a heightened state of alert."
Uniformed presence has increased in transportation hubs like Metro stations and airports.
Building Owners and Managers Association International, a trade group, said on Tuesday, "BOMA International and its members remain vigilant in maintaining the safety of their tenants and their properties."
BOMA has been working with the federal government since September 11 to coordinate emergency and security responses.