The FBI thwarted a plot targeting Sunday's UFC event at the White House and has arrested five men, the US justice department said on Tuesday.
Part of the plan involved striking nearby buildings with explosive-laden drones and firing on "high value targets", prosecutors alleged.
One suspect was arrested in Ohio last week, where investigators reviewed encrypted messages involving other alleged conspirators. Prosecutors said in charging documents they had allegedly "expressed ultra-religious and antigovernment sentiments".
"Allegedly planned attacks were stopped cold," FBI Director Kash Patel posted on social media on Tuesday about the "multi-state operation".
The suspects were identified as Tycen C Proper, 19, the suspect arrested in Ohio, along with Bryan Omar Roa, 24, and Michael Alan Thomas, 32, of California, Daniel K Eskridge, 32, of Missouri and Abraham Hermosillo Alvarez, 31, of Nebraska. They were arrested across the four US states and each have been charged with conspiracy to commit murder, the Department of Justice (DOJ) said in a statement.
By using the drones, the plotters aimed to spark panic and draw the fleeing crowd toward a sniper team, according to the court documents. A "second wave" of attackers was then allegedly supposed to storm the White House gate.
An estimated 4,300 people were present for the invite-only event on the South Lawn - and another 85,000 were able to watch nearby - during the back-to-back fights on Sunday.
Court filings related to Alvarez said the group allegedly eyed potential targets that included US President Donald Trump, Vice President JD Vance, Israeli Prime Minister Benjamin Netanyahu and Elon Musk, as well as several elected officials - though not all attended the UFC event.
The plot was discovered through Proper. His mother called local authorities late on 10 June - just days before the high-profile event - because she was concerned about his large firearms purchases and what she had seen of his online communication with a group that claimed to be made up of former military members and Christian-based.
The group allegedly wanted to "jumpstart" a revolution by shooting "high-value targets" - identified as wealthy people and politicians - attending the UFC fight. They had specifically discussed "grievances about government corruption, the handling of the Epstein files, data centers taking up all the water in communities, and other government actions," prosecutors said.
Group members stated that they wanted "to protect the United States, which they believed was headed in the wrong direction", an FBI document said.
"Members of the group believed that the United States needed to be torn down so that it could be rebuilt," the document said.
During an FBI interview on 11 June, Proper admitted to being part of planning the attack and said the group began communicating with one another around March through a TikTok group called "Vanguard of the Old", which is named in some court documents as "Vanguard of the Old Republic".
It is unclear if the group is affiliated with any larger, established organisation. But Proper told law enforcement officials that members were primarily recruited through TikTok.
Those who were "vetted" by other members moved to discussions on Signal, the encrypted messaging app, according to prosecutors. Prosecutors said a main chat had about 19 people in it, with smaller chats of four to five based on people's roles or locations.
Thomas allegedly envisioned a four-tiered operation, ranging from a top group that would "be sacrificing for your country, and carrying a brunt of the weight" by possibly breaking the law and going into hiding, to a fourth, less-active, tier made up of funders, influencers and others.
The documents described other chats where group members allegedly discussed assassinating several US lawmakers and prominent business executives. Some lawmakers were suggested "based on the group's perceived belief that the legislators accepted money from pro-Israel lobbies" and Eskridge allegedly described one as "big and someone a majority of the country knows".
The DOJ said Alvarez was responsible for planning, organising and directing the planned UFC attack, and that he worked on drones.
The suspects also distributed maps of Washington highlighting planned sniper locations and drone launch points and identifying power grids as potential targets, court documents said. Images in the filings show social media posts with tactical gear, weapons and maps.
"Proper said that although he was not going to the protest in order to shoot people, several other members of the group were intent on violence," the complaint against him said.
The BBC has contacted Proper's lawyer.
At an unrelated briefing on Tuesday, Secret Service Deputy Director Matt Quinn was asked about the thwarted incident and described it as a "serious threat," but did not offer many details, saying the case was ongoing.
He also appeared frustrated by how the investigation was made public, saying: "I'll tell you a phrase I learned early in my career in the New York field office and that's 'Don't choke on your own smoke.'"
"In order to maintain the integrity of the investigation and the security plan, we chose not to leak it," he added.
When asked about the alleged plot during the G7 summit in France on Tuesday, President Trump said: "I haven't heard about it."
Each suspect faces a maximum penalty of life in prison and a $250,000 (£186,122) fine if convicted of conspiracy to murder, the DOJ said. Proper faces three additional charges, according to court filings, including the charge of conspiracy to commit violence on White House grounds, which carries a maximum penalty of five years in prison.
A preliminary hearing has been scheduled for 29 June.
On Sunday, as part of the celebration of the nation's 250th anniversary, the White House hosted a series of Ultimate Fighting Championship (UFC) matches in an outdoor arena known as The Claw.
The event coincided with Trump's 80th birthday, and came two months after a shooting at the White House Correspondents Dinner that he attended and one month after a man was killed by Secret Service agents after opening fire at a White House checkpoint.
Political violence is on the rise in the US, Erica Frantz, a Michigan State University professor of political science, told the BBC. It tends "to be cyclical, where one act of violence often leads to another one", she added.
Targeted violence in the US grew more than 30% from 2024 to 2025, the National Consortium for the Study of Terrorism and Responses to Terrorism (START) found.
"There will always be disgruntled members of society who advocate conspiracy theories and extremist views that together don't make much sense," Frantz said. "I am less concerned with the specific motivation, and more concerned with the societal forces pushing people to the fringe."
With additional reporting by Nardine Saad
