Republican presidential candidate Donald Trump was rushed off stage by Secret Service officers on Saturday after a false gun scare during a campaign appearance in Reno, Nevada.
The US Secret Service later said someone in the crowd had shouted "gun" but that no weapon was found.
Local media reported that a suspect who was wrestled to the floor during the incident had been released.
The 70-year-old real estate tycoon returned just minutes after the incident to a cheering crowd, declaring "nobody said it was going to be easy for us, but we will never be stopped, never ever be stopped."
"I want to thank the Secret Service. These guys are fantastic. They don't get enough credit. They don't get enough credit. They are amazing people."
Trump could be seen shielding his eyes from the lights to peer into the crowd as a struggle broke out just a few moments before the incident.
Secret Service agents led Trump away, but once the suspect was in custody Trump returned to resume his speech.
"Mr Trump was removed from the stage by his Secret Service protective detail after a commotion occurred in the crowd," the Secret Service said.
"Immediately in front of the stage, an unidentified individual shouted 'gun'. Secret Service agents and Reno Police Officers quickly apprehended the subject."
"Upon a thorough search of the subject and the surrounding area, no weapon was found," the statement continued.
"A thorough investigation is ongoing at this time by the US Secret Service and the Reno Police Department."
Television footage showed a suspect detained on the ground by officers and searched before he was led away by local law enforcement.
The candidate appeared undisturbed and spoke with his usual self-confidence, finishing his prepared remarks and accepting applause before returning to his plane safely.
— Donald J. Trump (@realDonaldTrump) November 6, 2016
In a campaign statement, Trump thanked the Secret Service "and the law enforcement resources in Reno and the state of Nevada for their fast and professional response."
This marks the second time that Trump has been rushed off stage by security during the long, sometimes tense, campaign season, and his events are often disrupted by protesters.