A protester attending the Donald Trump rally at the Tucson Community Center was caught on video being "sucker punched" as he was being escorted out of the building on Saturday.
Tucson police said they arrested Tony Pettway, 32, on suspicion of misdemeanor assault with injury.
Bryan Sanders said he was punched and kicked as he was being escorted out. He said the "Trump is bad for America" sign he was carrying was ripped out of his hands.
The punch was caught in news video and photographs and has spread widely on the internet.
In a video interview after he left the rally he said the crowd was like an angry mob.
“I was protesting Donald Trump’s fascism, his racism, his lies and his women hating,” said Sanders. “Trump is bad for America.”
“This is not going to continue. If it takes somebody getting punched in the face, that’s what it takes,” Sanders said.