As propaganda videos released by ISIS celebrate the deadly attacks in Paris and threaten to carry out another attack in Washington, D.C., the presence of local law enforcement remained heightened on Monday in the District.
A senior U.S. official told NBC News that the video had not yet been verified.
"It looks like a typical propaganda video, and it's getting attention now because ISIS has been in the news," the official said.
Protecting the nation's capital, D.C. police have unique experience working with the federal government to keep people safe, Mayor Muriel Bowser said. Despite that YouTube video from ISIS, police said they are unaware of any credible threat to the city.
Regardless, the city is on guard.
"We take every threat seriously," Bowser said. "Our city is always at a heightened level of alert."
While there are no specific threats against the Capitol, lawmakers and their aides should use the tunnels between congressional buildings and take other precautions, Capitol Police said in a memo to lawmakers' offices Monday. The memo urges those who work for Congress to make sure their offices know where they are.
Capitol Police "increased presence and visibility" at the Capitol complex following Friday's attacks. Police also called on people working on Capitol Hill to report anything suspicious.
The Metro Transit Police Department continued additional patrols Monday following Friday's terror attacks. Riders will likely notice an increased police presence in the system, police said in a release Monday afternoon.
Metro Transit Police began extra patrols after the attacks Friday evening. The department also planned to conduct extra K9 sweeps in and around Metro stations and other areas, as well as random explosives screenings at entrances to Metro stations.
"Any bag or package carried onto the system may be subject to screening by MTPD officers," Transit Police said in a release Monday.
Chief Ron Pavlik said that doesn't mean going into riders' bags.
He urged riders to remain vigilant.
“See something say something is not white noise," he said. "We can’t allow it to become white noise.”
Transit Police and its law enforcement partners also enacted several other measures not visible to the public, they said.
Any Metro riders who see suspicious activity or unattended items should immediately call Transit Police at 202-962-2121 or texting "MyMTPD." Transit Police suggest riders should program MTPD's number into their cell phone. In an emergency, riders should call 911.
"Particularly now, we really do want to know about unattended items, people that just don't look like they belong," Amtrak Police Chief Polly Hanson said.
On Amtrak, the way to do it is by texting APD11.
Regarding the video threat, Hanson said, “I don’t think we need a video to tell us that D.C. is a target.”