Authorities say the suspect, identified as 31-year-old Cole Tomas Allen of California, is believed to have been targeting members of the Trump administration, according to a report by the Guardian.

Acting US Attorney General Todd Blanche said early findings suggest administration officials were the primary targets, with possible additional charges, including attempted assassination, still under consideration.

Allen was arrested after firing a shotgun at a Secret Service agent at a security checkpoint inside the Washington Hilton.

The agent was not seriously injured, with the bullet stopped by protective gear.

Officials said Allen is expected to be arraigned in federal court on charges including assault on a federal officer and attempted murder of a federal officer. The suspect remains in custody.

Investigators are also reviewing a manifesto attributed to Allen, which, they said, outlined grievances against the US administration and listed intended targets.

The document, which US media say has been verified by officials, did not explicitly name Trump but referred to broader political grievances and recent government actions.

According to reports, Allen sent written messages to relatives shortly before the attack expressing anger at the administration.

One family member later contacted police in Connecticut, prompting federal authorities to be alerted.

The suspect is also said to have described himself in writings as the “Friendly Federal Assassin” and referenced ideological and political motivations, including criticism of US foreign and domestic policy.

Allen travelled from California to Washington by train days before the event and checked into the hotel where the dinner was being held.

President Donald Trump, who was evacuated along with the first lady and senior officials, later described the attacker as a “sick person” but said he was not personally alarmed during the incident.

The investigation is ongoing, with federal authorities examining the suspect’s movements, online activity and communications with family members to determine the full motive and whether further charges will be filed.