Donald Trump was rushed off stage by Secret Service agents at a Nevada rally after a man close to the podium shouted: "Gun!"
The Republican US presidential nominee was speaking to supporters at the rally in Reno when a disturbance broke out in the crowd near the stage. Two agents quickly surrounded Trump and hustled him away.
In a statement, the Secret Service said a person in front of the stage had shouted "Gun!" but no weapon was found after a search. The person was apprehended and an investigation was taking place, it added.
Upon his return to the stage a few minutes later, billionaire Trump thanked the Secret Service and told the crowd: "Nobody said it was going to be easy for us. But we will never be stopped. Never ever be stopped."
The Secret Service statement said that magnetometer screening was used at presidential campaign sites and all general public attending must go through this prior to entering.
Don Trump and Dan Scavino, who runs Donald Trump's social media operation, re-tweeted a message that appeared to suggest that this was an assassination attempt.