By Jeremy Diamond CNN

WASHINGTON (CNN) -- Donald Trump on Saturday was rushed off the stage by Secret Service agents in the middle of a campaign speech here after an incident near the front of the stage.

It was not immediately clear what happened.

The Republican nominee returned to the stage several minutes after the incident.

"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.

Moments after Trump was rushed off stage, a SWAT unit of police officers showed up at the front of the crowd.

At least one man was detained and carried away by police officers and Secret Service agents.

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

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