Vice President Biden's office also confirmed that he had been briefed by telephone on the situation by his national security adviser. Biden was traveling to South Carolina for a speech on infrastructure.

Earlier Monday, the Navy said that several people were injured and that there were reports of fatalities after a shooting inside the Naval Sea Systems Command Headquarters that began Monday morning. The Navy has ordered staff on the scene to "shelter in place" at the headquarters, where around 3,000 people work.

The Capitol Police and D.C. Metropolitan Police Department were among those offering support and assistance on the scene, according to news releases. Additionally, the Capitol Police said they would increase security operations on the Capitol Grounds.

The Federal Aviation Administration has also grounded flights at Ronald Reagan Washington National Airport, as the shooter remains at large.

It appears that President Obama might still deliver remarks about the economy later in the morning from the White House. That event was moved in the morning from the Rose Garden to the South Court Auditorium although the White House provided no explanation for the change in venue.

— Updated at 11:59 a.m.