Republican presidential nominee Donald Trump was rushed off a stage at a rally in Nevada, a US state, by Secret Service agents during a campaign speech after an unruly incident in the crowd took place near the stage, media reported.

A scuffle could be seen breaking out in the audience, but it was not immediately clear what happened, reports CNN.

A law enforcement official told the media that no weapon was discovered. Trump was apparently unharmed and returned to the stage minutes later to finish his speech.

Trump was in the middle of his stump speech when the incident occurred. He then looked into the crowd, his hand over his eyes to block the glare from the stage lights, when Secret Service agents grabbed him and escorted him off the stage. Trump ducked his head as he left the stage.

The crowd surged backward, some supporters with frightened looks on their faces, as the Secret Service and police tactical units rushed in to detain a man.

The detained man was then rushed by a throng of police officers, Secret Service agents and SWAT officers armed with assault rifles to a side room.