Investigators suspect the attack may have stemmed from mental instability, although officials are continuing to examine whether there was any political motive behind the incident.
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A court order had earlier barred Best from approaching the White House premises, but reports said he violated the restriction.
Shooting near White House checkpoint
The shooting took place on 24 May(Indian Standard Time), shortly before 6 pm, near a security checkpoint outside the White House complex.
According to the Secret Service, Best approached the checkpoint and suddenly opened fire at officers.
One bystander was struck during the shooting and suffered serious injuries. Authorities are still trying to determine whether the bystander was hit by the suspect’s gunfire or during the exchange of fire with officers.
Members of the Secret Service’s uniformed division responded by returning fire and neutralising the gunman at the scene. Best was later taken to hospital, where doctors declared him dead.
No Secret Service personnel were injured in the incident.
US President Donald Trump was inside the White House residence at the time and was not harmed, officials said. A White House official added that Trump had been briefed on the incident.
FBI joins investigation
Reacting to the incident, FBI Director Kash Patel said federal authorities were assisting in the investigation and would release further details once available.
“FBI is on the scene and supporting Secret Service responding to shots fired near White House grounds - we will update the public as we’re able,” Patel said in a post on X.
White House briefly locked down
As per reported by CNN, members of the press were rushed into shelter as agents shouted “get down” and warned of “shots fired”. Armed Secret Service personnel carrying rifles were later seen moving across the White House grounds as security teams sealed off the area.
The lockdown remained in place for around 40 minutes before it was lifted shortly after 6:45 pm ET.
Several senior Trump administration officials, including White House Chief of Staff Susie Wiles, Treasury Secretary Scott Bessent and Vice President JD Vance, had reportedly left the White House shortly before the shooting took place.
Incident comes weeks after earlier security scare
The latest shooting comes less than a month after another security scare near the White House Correspondents’ Dinner, when a suspect carrying a shotgun allegedly exchanged fire with Secret Service officers after running through a security checkpoint.
The suspect in that case, Cole Tomas Allen, later pleaded not guilty to charges including attempting to assassinate Trump.