US law enforcement on Tuesday said it had foiled a plot to attack the White House during a crowded mixed martial arts event attended by President Donald Trump and other top officials.

"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," FBI Director Kash Patel announced on X.

His post included a caption of a Fox News headline reading: "FBI disrupts alleged explosive-drone plot targeting White House UFC event, officials say."

Trump on Sunday joined thousands of fans at the unprecedented White House fights, where a temporary arena dubbed "The Claw" was erected on the South Lawn.

Fox News reported that five people had been taken into custody, according to unnamed US officials, with investigators identifying 23 people in a "potential network of plotters" who allegedly communicated in a Signal group chat.

The plan allegedly would have involved using drones to hit buildings near the White House during the Ultimate Fighting Championship (UFC) contest, thereby prompting a mass evacuation that would "steer crowds toward a pre-staged sniper team," Fox News said.

There were also allegedly plans to storm the White House gates with a "second wave," the report said.

It was not clear if people involved in the alleged plot had taken any steps to carry out an attack. The White House is protected by intense surveillance, fencing, checkpoints, anti-air-attack capabilities, snipers and a permanent group of quick-reaction forces.

Asked for further details about Patel's announcement, the FBI told AFP "we have nothing to add to the post at this time."

Vance targets left

The June 14 "UFC Freedom 250" event -- which also fell on Trump's 80th birthday -- was meant to kick off this year's festivities for the 250th anniversary of US independence.

Fox News reported that the FBI learned of the threat on June 10.

"Protective intelligence cases are on the rise, and our teams work tirelessly behind the scenes to investigate threats, identify those responsible and ensure accountability," the US Secret Service said in a statement on X.

"In the days leading up to this weekend, our special agents, mission support personnel, and technical security teams worked around the clock to identify those responsible and hold them accountable," Secret Service Director Sean Curran said.

Trump has faced several assassination attempts in recent years, most recently when a gunman attempted to storm a White House press gala he was attending in April.

US Vice President JD Vance, who also attended the UFC event, said Tuesday morning in an appearance on Fox News that he had just learned about the alleged plot.

Asked why the FBI revealed the foiled plot -- a step it does not always take for various security reasons -- Vance pointed to potential "scale of the planned attack."

He described the alleged plan as a "coordinated planned terrorist plot" and cited the Trump administration's work to investigate funding and coordination networks of radical left-wing groups.

Vance did not provide further details on who the alleged suspects were or their motivations, but nonetheless accused Democrats of fomenting violence with anti-Trump rhetoric.

"Everybody has a role to cut this stuff out, but I think a lot of my Democratic colleagues in Washington have got to look themselves in the mirror and say, 'why is so much of this political violence coming from our side of the spectrum?'" he said.

The White House has repeatedly claimed that Trump critics and the media are responsible for rising political tension in the country. Opponents of Trump say the 80-year-old Republican's often inflammatory rhetoric against opponents, immigrants and the election system are to blame.