The plot involved using explosive-laden drones to strike the north side of the White House with the aim of funnelling attendees toward an ​exit where snipers planned to open fire on fleeing politicians and others, the FBI alleged in court ​papers.

US President Donald Trump attended the event, which was staged without incident on his 80th birthday, ⁠along with several senior Republican lawmakers, donors and administration officials to commemorate the 250th anniversary of US independence.

The five ​people charged appeared to subscribe to anti-government conspiracy theories and were motivated in part by anger at the handling ​of investigative files related to sex offender Jeffrey Epstein, according to court documents.

One person charged expressed interest in targeting lawmakers who had received campaign donations from pro-Israel groups, the documents said.

“On June 10, the FBI and our law enforcement partners became aware of a potential threat ​to the UFC America 250 event in Washington, DC, involving individuals outside of the National Capital Region,” FBI Director ​Kash Patel said in a statement posted on X.

At least three of the five taken into custody have been charged with ‌conspiracy to ⁠commit murder. Other charges facing the group include conspiracy to commit an offence against the United States and weapons offences.

They have not yet entered pleas in court, and attorney information was not immediately available.

Fox News Digital reported that the group included as many as 23 people.

Authorities discovered the plot when the mother of one of the suspects, 19-year-old Tycen ​Proper, called local police in ​Ohio to report that ⁠her son had made several weapons purchases and was interacting with concerning people online.

Proper later admitted to FBI agents that he was aware of a planned coordinated attack ​on the UFC event, according to an FBI affidavit.

Trump, at the Group of Seven ​summit in Evian, ⁠France, said he had not heard about the planned attack.

Vice President JD Vance said authorities were trying to look at the underground networks that would drive such violence.

“Twenty-three people do not get to the point where they’re going to commit a ⁠mass ​terror incident in Washington, DC, without some serious funding, without some serious ​coordination,” Vance said in a Fox News interview.

“That’s not a few guys doing crazy stuff, that is a coordinated, planned terrorist plot,” he said.