Police "probably" thwarted a potential third assassination plot against former President Donald Trump, a Sheriff has claimed.

Riverside County Sheriff Chad Bianco spoke during a press briefing tonight and became visibly defensive when probed about the veracity of an earlier depiction of the Saturday Coachella rally incident as "dramatic."

Bianco confirmed that 49 year old Vem Miller was intercepted at the innermost security checkpoint of the rally, driving a vehicle with counterfeit number plates.

Upon further inspection, officers uncovered a loaded shotgun, a loaded handgun, and numerous fake identities in Miller's possession, reports the Express US.

"He showed up with multiple passports with different names, an unregistered vehicle with fake license plate and loaded firearms," Bianco asserted in response to suggestions that his initial account may have been overstated.

He went on to underscore the gravity of the situation, adding: "If you are asking me right now, I probably did have deputies that prevented the third assassination attempt.

"If we are that politically lost that we have lost sight of common sense and reality and reason that we can't say 'Holy crap, what did he show up with all that stuff for? And loaded guns?'

"And I'm going to be accused of being dramatic. We have a serious, serious problem in this country because this is common sense and reason. I saw some of you there yesterday - you didn't have guns and fake IDs."

Bianco went on to describe the suspect as a "lunatic," and said possible far-right links were being considered.

The Secret Service has since said "the incident did not impact protective operations and former President Trump was not in any danger."

Vem Miller, who is from Las Vegas, was arrested at around 5pm and charged with possession of a loaded firearm and a high-capacity magazine, according to the Riverside County Sheriff's Office. Trump took to the stage located just east of Los Angeles at 5.37pm.

The suspect was driving a black SUV at the time of his arrest. He was released later on Saturday on a $5,000 bail.

No federal arrest - which would indicate more serious charges - has been made though the Secret Service and FBI are investigating the incident.