The mammoth operation was alleged to have a number of stages designed to wreak havoc on the presidential event
A bomb plot targeting thousands of people at Donald Trump's White House UFC event was "stopped cold" by the FBI.
Five people were taken into custody while top officials identified 23 individuals as part of a possible network of plotters.
The alleged plan was to deploy drones carrying explosives to hit buildings close to the Washington event, which would trigger mass evacuations.
From there, the fleeing crowds would be guided towards a pre-staged sniper team, officials added.
Then, the next stage of the plan allegedly involved another group storming the gate towards the White House.
But, before the plot could go ahead, America's top detectives revealed Signal chats where individuals allegedly spoke about the event.
Officials said one device revealed 23 people talking about "pre-operational activity", with some believed to be planning to travel to Virginia on June 12 or June 13.
The aim was to target "capitalist elites and billionaires", as well as politicians who had donations from the American Israel Public Affairs Committee, one suspected admitted.
After clamping down on the alleged scheme, FBI Director Kash Patel heaped praise on the bureau, the Department of Justice and law enforcement partners for their fast response.
"Thanks to the rapid action of this FBI, our partners, and the Department of Justice in a multi-state operation, multiple individuals are now in custody and allegedly planned attacks were stopped cold," Mr Patel told Fox News.
"While the result represented the best of investigative work, it was also nothing out of the ordinary for this law enforcement team," he added.
"We are built to detect, respond to, and bring to justice those who threaten the lives of American citizens — particularly during large gatherings like the historic UFC 250 fight. That’s exactly what we did here."
"I want to thank our great agents and partners, this work remains ongoing, and we will continue to update the public as permitted," he said.
UFC Freedom 250 took place on Sunday on the South Lawn of the White House to commemorate the 250th anniversary of American independence.
It was hailed as a major event as US Secretary of State Marco Rubio said the fight would be watched by a "billion people all over the world".
Describing the event as a "gift to the American people", he added: "The White House is the people's house. It belongs to the people of the United States.
"The American 250 celebration belongs to the people of the United States."
The Sunday event attracted around 4,300 attendees, as well as 1,200 service members on duty for the high-profile event.
A signature octagon cage was built on the South Lawn, with the US administration saying the UFC would be covering the eyewatering £45million cost.
As part of the celebration, 14 international fighters took part in a cagefight in the evening in what Mr Trump lauded as the "greatest show on earth".