The alleged ringleader of a terror plot to attack President Donald Trump's White House UFC event is an illegal immigrant from Mexico, officials said.

Abraham Alvarez, 31, arrived in the US as a child and failed to leave after his B2 visa expired in 2001, the Department of Homeland Security (DHS) said. 

According to the department he was later granted relief under the Obama administration's Deferred Action for Childhood Arrivals (DACA) program. 

Alvarez, who is said to have used the code name Shepherd, was nabbed by authorities in Omaha, Nebraska, on Sunday following a raid on an abandoned church. 

Authorities said he had told others implicated in the alleged attack to meet at the church, deeming it a safe zone. 

DHS said that Alvarez, and five other suspects, face federal charges of conspiracy to commit murder and conspiracy to commit violence on White House grounds. 

Acting Assistant Secretary Lauren Bis said: 'This illegal alien from Mexico should never have been allowed in our country. 

'He was the ringleader of a failed terror attack targeting UFC Freedom 250 at the White House. He will face justice and swiftly be removed from our country.'

Investigators believe the group planned to strike buildings near the event with drones packed with explosives, triggering a mass evacuation. 

Authorities believe the plan was to send the panicked crowds towards a pre-positioned sniper team as they tried to escape. 

Alvarez is one of five individuals now in custody, with authorities saying they have identified 23 others as being involved. 

Some of the suspects allegedly planned to travel to Fredericksburg, Virginia, on June 12 and 13 to make final preparations ahead of the attack. 

One suspect allegedly told investigators the goal was to target 'capitalist elites,' 'billionaires' or politicians who received donations from the American Israel Public Affairs Committee. 

One of the central figures identified by prosecutors is 19-year-old Ohio resident Tycen Proper.

According to an FBI affidavit, Proper admitted participating in discussions about an attack that authorities say was intended to 'jumpstart' a revolution in the United States. 

Two California men, Michael Thomas, 32, and Bryan Roa, 24, were arrested over the weekend in the Golden State over the weekend.

According to a complaint filed in federal court, the two had met in person to practice their marksmanship. 

Daniel K. Eskridge, 32, of Missouri, was also arrested in connection with the investigation. 

Officials claimed he sent images of tactical gear, a rifle, helmet and a ballistic vest to a Signal group chat that the suspects were all part of.

The probe began after a relative of one suspect contacted police in the Cincinnati area with concerns about comments involving a possible plot in the nation's capital.

Investigators subsequently obtained access to encrypted Signal communications and uncovered discussions about drones, snipers and an attack targeting the UFC event.

The charging documents describe a mix of anti-government beliefs, conspiracy theories, antisemitic grievances and anger over the Trump administration's handling of files connected to convicted sex offender Jeffrey Epstein. 

Held on Sunday night on the South Lawn, UFC Freedom 250 was promoted as part of celebrations marking America's 250th anniversary.

The event also coincided with Trump's birthday and drew significant crowds to the White House grounds.

Neither Trump nor Vice President JD Vance were briefed on the alleged plot beforehand, according to comments made earlier on Tuesday.