A California man has been charged with attempting to assassinate US President Donald Trump in an incident that has sparked a White House security review.

Cole Tomas Allen, 31, was also charged with two firearms offences when he appeared in court in Washington DC on Monday. He did not enter a plea.

He was carrying a semi-automatic handgun, a pump-action shotgun and three knives as he charged past a security checkpoint at the White House Correspondents' Association dinner on Saturday, say prosecutors.

A Secret Service agent was hit but not seriously wounded during the attack at a hotel. The accused faces life in prison if found guilty. He is due to appear in court again on Thursday.

Dressed in a blue jumpsuit with a nametag for Monday's court appearance, the suspect appeared calm and was softly spoken as he answered almost every question from the judge with either "yes, your honour" or "no, your honour".

He stated his age and said he had a master's degree.

Reporters in court said the defendant seemed to closely observe the proceedings, and looked directly at the judge during questions.

Three US marshals stood behind him, and one was at his side, while the federal prosecutor handling the case, US Attorney for Washington Jeanine Pirro, looked on.

During Saturday night's incident, Trump, Vice-President JD Vance, cabinet members and other White House senior figures were rushed from the Washington Hilton hotel ballroom after gunfire rang out.

The suspect allegedly rushed through a security checkpoint one floor above the basement venue.

"One Secret Service officer was shot in the chest, but was wearing a ballistic vest that worked," Acting Attorney General Todd Blanche told a news conference on Monday.

"This heroic officer who was hit fired five times at Allen, who was not shot but fell to the ground and was promptly arrested."

Blanche said the suspect is believed to have discharged his shotgun at least once.

It is not clear whether the Secret Service agent was shot by the suspect, or was caught in crossfire from other law enforcement. The Secret Service agent has been released from hospital. Pirro said he had a knee injury.

The court heard that the accused had crossed multiple state lines in order to try to kill Trump.

He is said to have left his home in the Los Angeles area on 21 April, travelling by train to Chicago.

On 24 April, he left Chicago, and arrived in Washington where he checked into the Hilton.

The following day, he walked to the event checkpoint, and "ran through while holding a long gun", said Blanche.

The suspect studied at the prestigious California Institute of Technology, and worshipped at the Pasadena United Reformed Church in the Los Angeles area.

Federal campaign finance records show he donated $25 to a Democratic Party political action committee in support of Kamala Harris for president in 2024.

Attempting to assassinate the president carries a potential life sentence.

The other charges - transportation of a firearm between states to commit a felony and discharging a firearm in a crime of violence - both have maximum sentences of 10 years.

At Monday's news conference, Pirro said the suspect's intent, based on writing he sent to his family before the attack, was to bring down as many high-ranking cabinet members as he could.

Prosecutors requested that Allen remain detained, arguing that the assassination attempt charge could be considered terrorism. Pirro said more charges could be filed.

As US investigators look into the third alleged assassination attempt against Trump, security officials are reviewing how the situation was handled, and how to beef up protection of the president.

Many have questioned whether the security perimeter at the Washington Hilton was strong enough, why attendees were never asked to show identification at the event, and why the president, vice-president and others in the line of succession were all gathered in one place.

In Monday's news conference, Blanche maintained that "law enforcement did not fail" in its job to protect the event.

He noted that one thing should be "clear" - the gunman was one floor away, "with hundreds of federal agents between him and the President of the United States".

A senior White House official told the BBC that Trump was "standing by" the leadership of the Secret Service, an arm of the Department of Homeland Security (DHS) that protects high-level government officials.

White House Chief of Staff Susie Wiles will convene a meeting this week to "discuss protocol and practices for major events", the official also said.

At a news briefing on Monday, White House Press Secretary Karoline Leavitt said Trump "believes the protocols worked" for security on Saturday and blamed rising political violence on the rhetoric of Democrats.

Trump has offered assurances that King Charles III will "be very safe" during his four-day state visit to the US, which began on Monday at the White House.

The president's security detail must meanwhile prepare for a rescheduling of the White House correspondents' dinner.

FBI Director Kash Patel told Fox News on Monday that "we're going to be so ready" for Trump to attend the event in the next 30 days and that "the security posture, I imagine, is going to be completely different".

No new date has yet been set for a second try at the annual dinner.

Preparations for the event typically take months.

The Washington Hilton, where John Hinckley Jr attempted to assassinate then-President Ronald Reagan 45 years ago, said it followed security instructions from the Secret Service.

"The hotel was operating under stringent security protocols for the property as directed by the US Secret Service, which led security for the event," it said in a statement, according to Reuters, adding that it had worked with local police and other security teams.