As Barack Obama took the oath of office to become the 44th President of the United States, the men and women of the FBI's Command and Tactical Operations Center paused briefly to witness the historic occasion – then it was back to work.
Millions of people arrived in Washington almost overnight for inaugural activities, but the FBI started planning security with law enforcement partners six months ago. The security coverage began Jan. 17 and continued throughout the events.
From the command center at the FBI's Washington Field Office, agents, analysts, administrators and members of their Joint Terrorism Task Force fielded tips from the public and used mapping and surveillance technology to track suspicious activity, as well as to monitor response teams on the ground near the Capitol and the inaugural parade route along Pennsylvania Avenue.
More than 150 plainclothes teams on foot and in vehicles were "our eyes and ears on the ground - our trip wires, if you will," John Perren, Special Agent in Charge of the Counterterrorism Division at their Washington office, said.
The command center - the hub of FBI communications activity - enabled teams in the field to share information in real time and allowed its staff to continually update the threat assessment.
Manning the operation were some of the Bureau's most "battle-tested" personnel, Joseph Persichini, Jr., who heads the Washington Field Office, said. "Many people in the room were here during 9/11 and responded to the Pentagon after the attacks."
FBI agents from the Washington Field Office with one of the tactical vehicles they had on standby.
Meanwhile, over at the Joint Information Center run by the U.S. Secret Service, more than 20 agencies handled all the media for security issues.
FBI special agents from the National Press Office helped field a flood of media calls on inauguration security in the U.S. Secret Service's Joint Information Center.
The FBI also worked shoulder-to-shoulder with several law enforcement partners to staff their strategic command center, or SIOC, at FBI headquarters during the inauguration.
the behind the scenes video of the FBI at work.