Republican presidential candidate Donald Trump was rushed off stage by Secret Service agents in the middle of a campaign speech at a rally in Nevada on Saturday night.

It was not immediately clear what happened but an incident near the front of the stage caused stirs.

The Republican nominee returned to the stage again amid the cheering crowd about five minutes later, saying he cannot be stopped and thanking the Secret Service agents.

“Nobody said it was going to be easy for us, but we will never be stopped. We will never be stopped. I want to thank the Secret Service. These guys are fantastic.”

He then returned to his regular stump speech.

In a statement later, Trump said, “I would like to thank the United States Secret Service and the law enforcement resources in Reno and the state of Nevada for their fast and professional response.

“I also want to thank the many thousands of people present for their unwavering and unbelievable support.

“Nothing will stop us – we will make America great again!”

Trump was peering into the crowd just before his speech was interrupted, and law enforcement agents then made their way into the crowd towards what appeared to be some sort of disruption.

Two security agents grabbed Trump by the shoulders and rushed him back stage.

The threat was unclear, but a man near the front of the crowd was pounced on by other security agents.

Moments after Trump was rushed off stage, a Special Weapons and Tactics (SWAT) unit of police officers showed up at the front of the crowd.

While it wasn’t clear who was responsible for the interruption or what they did, a man was led away in handcuffs by police.

The man was held in the back of the venue with officers inside with him and outside on guard.

According to local law enforcement, someone shouted out that a man had a gun in the crowd, though it was still unconfirmed as at press time.

Several attendees at the rally said they saw a Trump supporter raise up a sign and then a scuffle ensued.

Trump had paused his stump speech to call out a protester when several Secret Service agents suddenly rushed to him and grabbed him off the stage.

Chaos ensued as the crowd began to rush away from the stage; some rushed back toward a barricaded area where the press corps was set up and began screaming at them.

As rally attendees began to fearfully race for the exits, Trump aides rushed to the candidate’s travelling press corps and ordered them to immediately rush to the motorcade.

Reporters ran through the crowd and heavily armed police officers with machine guns were seen escorting a man backstage but they declined to comment to reporters about the incident.

Trump’s travelling press corps was initially rushed toward the motorcade, amid word from the campaign that the candidate would not return to the stage.

However, few minutes later, they were rushed back in the room, where the Republican presidential candidate had retaken the stage.

Meanwhile, a press bus carrying reporters covering Democratic vice-presidential candidate Sen. Tim Kaine was hit at high speed in Florida, according to reporters traveling with the senator.

There were no immediate reports of injuries.

Kaine had a stop at Florida, a battleground state that is a must win for Democratic nominee Hillary Clinton as the battle for the White House reached an all-time tight.

Trump was in Nevada, seen as one of the swing states, to rally for votes in the last legs of the campaign that has seen him running neck-and-neck with rival Clinton.