Two Southern California men have been charged with conspiracy to commit murder in connection with an alleged plot to attack a UFC event held on the White House grounds, according to a federal criminal complaint.

The event was attended by President Donald Trump and other government officials. 

Bryan Omar Roa of Yucaipa and Michael Alan Thomas of Pinon Hills were charged Sunday in the Central District of California after federal investigators linked them to what authorities describe as a broader anti-government conspiracy targeting UFC Freedom 250, which took place June 14 on the White House lawn.

According to the complaint, members of the group discussed using drones carrying explosives to create panic among attendees and force crowds toward designated locations where armed shooters would be positioned to target government officials and other "high-value targets."

Federal investigators allege the conspiracy was motivated by anti-government beliefs and a desire to spark the collapse of the U.S. government through acts of violence.

The California charges stem from an investigation that began in Ohio after the family of 19-year-old Tycen Proper contacted authorities about his increasingly concerning behavior, firearms purchases, and communications with an online group.

Proper was later charged separately in the Southern District of Ohio and allegedly identified Roa and Thomas as participants in the plot.

According to the affidavit, investigators reviewed encrypted communications in which members of the group discussed sniper positions, drone launch sites, escape routes and operational planning for an attack timed to coincide with UFC Freedom 250, a public event attended by Trump and other government officials.

Authorities executed search warrants June 13 at the residences of Roa and Thomas.

At Roa's residence and vehicle, agents recovered an AR-style rifle, a Glock handgun, ammunition, a tactical belt, a two-way radio and other equipment, according to the complaint.

Investigators also seized his cellphone, which allegedly contained communications with other members of the conspiracy and searches for locations in Washington, D.C.

The complaint alleges Roa told investigators he intended to travel to Washington to protest the UFC event but denied participating in the conspiracy.

Family members told law enforcement they believed he planned to travel to the nation's capital and feared he intended to commit an act of violence.

At Thomas' residence, agents seized a hunting rifle, an AR-style rifle, extended magazines loaded with ammunition and a pistol, according to court documents.

Investigators said Thomas admitted helping plan the attack and described himself as a planner and adviser for the group.

According to the affidavit, Thomas told agents he wanted to guide others in carrying out attacks and believed the objective of the UFC Freedom 250 operation and future attacks was to create enough chaos to bring about the overthrow of the U.S. government.

The complaint also cites online communications allegedly exchanged by Thomas and other members of the group discussing operational roles, firearms training, logistics, and support for participants willing to engage in violent acts.

Federal agents allege Roa and Thomas met in Southern California in May to conduct firearms and tactical training.

Messages cited in the complaint show the two discussing marksmanship, movement techniques, and preparations for what Thomas described as "guerrilla style warfare."

Investigators also allege members of the conspiracy discussed raising money to purchase drones and explosives.

In one exchange cited in the complaint, a co-conspirator stated that $1,300 was needed for "the drones and the charges," while Thomas responded that he could contribute manpower but had little money available.

Authorities have identified multiple alleged members of the conspiracy across several states. The complaint states that additional suspects have been charged or arrested in other federal districts.