The Pentagon was placed on lockdown after multiple gunshots reportedly rang out by the facility's Metro station, leaving one officer dead.
According to The Associated Press, the officer was stabbed during the Tuesday morning chaos. Their source chose to speak on the condition of anonymity because they are not authorized to reveal information to the public.
It is not clear what order of events took place.
The journalist also alleged police were screaming out "shooter."
The Arlington Fire Department confirmed the scene was active mid-morning and revealed they encountered "multiple patients" upon arrival.
The Pentagon Protection Force Protection Agency tweeted about the incident and said the incident took place on a Metro bus platform that is part of the Pentagon Transit Center.
"Right now, we've just confirmed that the Pentagon is on lockdown. There is an incident at the Pentagon transit center," agency spokesperson Chris Layman stated.
The "incident is ongoing," he stated, adding the scene was not safe.
Layman also advised people to avoid the area with Metro subway trains being ordered to bypass the Pentagon.
At the time, personnel was not allowed outside the facility due to a "shooting event."
Layman refused to answer questions involving how many people were injured.
This is not the first time that gunshots have rang out near the Pentagon.
More than 10 years ago, two officers at the Pentagon Force Protection Agency were injured when a gunman approached them at the screening security area.
John Patrick Bedell died after officers returned fire in the 2010 shoot-out.