One of the most strategic sites in the United States was briefly placed on high alert.
Several shots rang out a few meters from the Pentagon and a police officer was killed, according to several American media.
The scene allegedly took place at the bus stop located right next to the famous building in Virginia.
Employees of the US Department of Defense were called over a loudspeaker to stay inside the building at around 10:40 a.m. local time.
The state of alert was lifted at around 12:10 p.m. but the exits of the metro station and the bus station, which are both a few meters from one of the Pentagon's entrances but are accessible to the public, remained. closed until further notice.
"The incident is over, the area is secure, and most importantly, our community is no longer threatened," Pentagon protection force chief Woodrow Kusse told reporters.
He said there were "several injured" but declined to confirm reports that one of his police officers died of stab wounds, while the assailant was shot and killed.
Pentagon protection chief says there were "several injured"
The Democratic Senator from Virginia Mark Warner, however, offered his condolences to the friends and family of the police officer.
"I am terribly saddened by the death of a Pentagon policeman, who was killed this morning in an insane act of violence," he tweeted.
I'm incredibly saddened to learn about the passing of a Pentagon police officer, who was killed earlier this morning in a senseless act of violence outside the Pentagon.
My heart goes out to the officer's family and friends, as well as the entire Pentagon Police force.
- Mark Warner (@MarkWarner) August 3, 2021
Local television channels showed in the afternoon dozens of police gathered in front of the Washington hospital where the officer had been transferred, to pay tribute to him.
The emergency services of Arlington, the commune where the Pentagon is located, seat of the Department of Defense and the command of the American army, indicated that "several patients" had been taken care of on the spot.
Defense Minister Lloyd Austin "was not in the building at the time of the incident," said spokesman John Kirby.
"The minister was informed of the incident at the Pentagon and he is regularly informed of all new developments," he added.
Lloyd Austin and Chief of Staff Gen. Mark Milley were in the White House for a weekly meeting with President Joe Biden.
