WATCH: Secret Service agents rush stage at Trump rally in Ohio

This is an archived article and the information in the article may be outdated. Please look at the time stamp on the story to see when it was last updated.

A group of U.S. Secret Service agents briefly formed a protective ring around Republican presidential candidate Donald Trump at his rally in Ohio, but then quickly left the stage and allowed him to continue his speech.

It was not immediately clear why the agents rushed onto the stage Saturday morning to surround Trump, who appeared to jolt after hearing something in the audience standing behind his right shoulder.

Four Secret Service agents then rushed onto the stage, as the audience chanted “Trump! Trump! Trump!” The agents quickly cleared.

Trump did not explain what happened, but said: “Thank you for the warning. I was ready for ’em, but it’s much better if the cops do it, don’t we agree?”

Both the Secret Service and Trump campaign staff did not immediately respond to questions seeking comment.

Trump was able to finish his speech and did so without apparent incident.

The billionaire businessman called off a rally on Friday night in Chicago, after protesters filled the arena where he was scheduled to speak.

Notice: you are using an outdated browser. Microsoft does not recommend using IE as your default browser. Some features on this website, like video and images, might not work properly. For the best experience, please upgrade your browser.