It was the third incidence of gunfire in the vicinity of President Donald Trump in the past month.
The man approached a checkpoint shortly after 6pm on Saturday, "removed a weapon from his bag and began firing at posted officers", the US Secret Service said in a statement.
Officers returned fire, hitting the gunman, who later died in hospital.
A bystander was also struck, but a law enforcement official said it wasn't clear whether that person was hit by the suspect's bullets or those fired by officers.
The Secret Service said none of its officers were injured, and that Trump - who was at the White House at the time - was not "impacted".
The gunman was identified as 21-year-old Nasire Best, according to a law enforcement official who spoke on the condition of anonymity.
Best was arrested in July 2025 after he tried to enter a different White House checkpoint without authorisation, didn't heed officers' commands to stop, "claimed he was Jesus Christ" and said he wanted to be arrested.
An initial hearing was held and a "Pretrial Stay Away Order" was issued, typically a measure ordering a defendant not to go near a person or area before a trial.
A bench warrant was issued in August after a notice of "noncompliance" against Best, who appeared for a subsequent hearing.
Journalists working at the White House on Saturday evening reported hearing a series of gunshots and were told to seek shelter inside the press briefing room.
In a social media post, FBI Director Kash Patel said officers were responding to shots fired and said he would "update the public as we're able".
In a post shared on X, Selina Wang, the senior White House correspondent for ABC News, shared dramatic video of the moment she said she heard what "sounded like dozens of gunshots" and ducked for cover.
Wang's video of the moment has since been viewed at least three million times.
The scene is near where a gunman ambushed two members of the West Virginia National Guard last November.
US Army Specialist Sarah Beckstrom, 20, died from her wounds. Andrew Wolfe, then 24, was critically wounded. Rahmanullah Lakanwal has been charged in that incident.
The gunfire on Saturday comes nearly a month after what law enforcement authorities said was an attempted assassination of the president on April 25 as he attended the annual White House Correspondents' Association Dinner at a Washington hotel.
Cole Tomas Allen, of Torrance, California, recently pleaded not guilty to charges that he attempted to kill Trump and remains in federal custody.
Following that scare, Secret Service officers shot a suspect they said had fired at officers near the Washington Monument, also near the White House.
Michael Marx, 45, of Midland, Texas, was charged in a complaint filed in US District Court in connection with the May 4 shooting. A teenage bystander was wounded in that incident.
with AP
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