A police officer was shot dead outside the U.S. Pentagon. The killing of the officer outside the headquarters of the U.S. Department of Defense sparked a shootout between responders and the suspect, resulting in the latter's death.

The officer was reportedly killed after a yet-to-be-identified assailant attacked a bus platform outside the U.S. military facility. Law enforcement sources said the suspect was killed by first responders on the scene.

Pentagon Force Protection Agency Chief Woodrow Kusse provided scant details about the incident and said that it was still under investigation. Kusse said there was nothing to indicate that the attack was motivated by terrorism.

He added that his agency does not want to share any details of the attack as of the moment as it might jeopardize their investigation. The FBI is currently leading the investigation into the incident. The Pentagon assured the public that the issue was resolved and they are not looking for any additional suspects.

The officer, who was not named, was reportedly attacked while he was on duty at a Metro bus platform just outside the Pentagon. Initial reports said there were "several casualties." The Pentagon said it would release more details once they have been verified "as soon as possible." The FBI also didn't provide any further details about the incident.

A reporter for the Associated Press who was near the Pentagon said he had heard multiple gunshots then a long pause, which was followed by another shot. Another journalist was able to take a video of the scene shortly after the shots were fired. The video showed two lifeless bodies surrounded by Pentagon Force Protection officers. The bodies were then carried away by emergency responders.

Defense Secretary Lloyd Austin expressed his condolences to the family of the officer that was killed. He also ordered the flags at the Pentagon to be flown at half-mast to honor the fallen officer. Austin said the officer died in the line of duty, protecting the people who work and visit the Pentagon every day.

The chairman of the Joint Chiefs of Staff, General Mark Milley, also issued a statement honoring the officer. He expressed his gratitude for the officer's dedication and courage. Senator Mark Warner condemned the killing and called the incident a "senseless act of violence."