Man arrested with weapons at Donald Trump rally identified as Vem ...

A man with a shotgun, a loaded handgun, ammunition, fake licences and fake passports in his vehicle was arrested at a security checkpoint outside a rally for Donald Trump in California, according to local police.

The arrest took place on Saturday, local time.

The suspect, identified as Vem Miller, a resident of Las Vegas, was driving a black SUV that was stopped by deputies assigned to the rally in Coachella, east of Los Angeles, the Riverside County Sheriff's Department said in a statement.

The 49-year-old was arrested on suspicion of possessing a loaded firearm and possession of a high-capacity magazine, the department said.

He was eventually released on bail and will appear in court over the state firearms charges at a later date. 

The man gave all indication he belonged there and was allowed in to the event as a member of the press, Riverside County Sheriff Chad Bianco told reporters. 

"We know he claimed to be a journalist, and he claimed to have VIP status to the event that got him into the perimeter, and when that investigation was continued by the deputy, that didn't necessarily materialise," Sheriff Bianco said.

"So other than his words that he was a journalist ... I can't tell you that he gave us a document and we said that was fake."

Media members, as well as VIP ticket holders, were routed through a number of intersections manned by state and local law enforcement officers before arriving at a large, grassy area where drivers were asked to open hoods and trunks, and each vehicle was searched by a canine officer.

Republican presidential nominee Trump holds a rally in Coachella.  (Reuters: Mike Blake )

Other general ticket holders were directed to a site roughly 5 kilometres away from the rally, where they were boarded onto buses and driven to the site.

Sheriff Bianco said he believed his deputies "probably prevented a third assassination attempt" by taking the man into custody. 

"If you're asking me right now, I probably did have deputies that prevented the third assassination attempt," he said.

"If we are that politically lost that we have lost sight of common sense, of reality, and for that reason that we can't say, 'Holy crap, what did he show up with all of that stuff for, and loaded guns?' and I'm going to be accused of being dramatic?

"Then we have a serious problem in this country."

He also praised the work of local deputies conducting checks on the outer perimeter of the rally. 

"Thank God, and by an act of really what we did in the week leading up to keeping that place secure, I certainly wouldn't want to be saying after the fact that I wish we would have done more to prevent that shooting," he said.

The sheriff declined to speculate about the suspect's motives or frame of mind. 

"We know we prevented something bad from happening, and it was irrelevant what that bad was going to be," he said.

"There is absolutely no way that any of us are going to truly know what was in his head."

Trump's campaign did not immediately respond to a request for comment on the arrest.

The sheriff said further investigations will be conducted by the FBI and Secret Service. 

The Secret Service said that it was aware of the arrest and that neither Trump nor rally attendees had not been in any danger during the incident.

"While no federal arrest has been made at this time, the investigation is ongoing," the organisation tasked with protecting presidents and presidential candidates said in a joint statement with the FBI and the US Attorney's office.

AP/ABC