Protesters were waving signs outside President Trump’s rally in downtown Cincinnati on Thursday when a red pickup truck pulled up to the crowd. Someone in the passenger seat started yelling, WCPO reported, and a few protesters shouted back. Suddenly, the door flew open and a man in a green polo hopped out, fists cocked.

As the crowd gasped and screamed, the man, later identified by local media as 29-year-old Dallas Frazier, landed a quick volley of punches to the face of Mike Alter, 61. Within a few seconds, a police officer rushed in to handcuff Frazier.

Another protester captured video of the beating, which quickly went viral.

Frazier has now been charged with assault, according to Hamilton County court records. He’s due in court at 12:30 p.m. on Friday, WXIX reported.

The confrontation came hours before another physical tussle ended with an arrest at a political rally 1,800 miles away in Tempe, Ariz. At a campaign event for Sen. Elizabeth Warren (D-Mass.), a man in the crowd was charged with assault after arguing with members the AZ Patriots, a conservative group, The Washington Post’s Annie Linskey reported. AZ Patriots members said he tried to grab one of their cellphones as the group was being escorted out of the rally, and police said the man, who hasn’t been identified, refused their orders to leave.

Trump has faced repeated accusations and legal claims that he has encouraged violence against protesters at his rallies. When demonstrators interrupted his speech inside U.S. Bank Arena in Cincinnati on Thursday, the president used the moment to further his recent attacks on big, liberal cities.

“You must have a Democrat mayor,” he told the crowd. “Come on, law enforcement.”

That protest ended peacefully, unlike the scene outside the arena.

Alter, who spoke with WCPO, said protesters had been yelling back and forth with a few Trump supporters headed into the event when the red truck approached and Frazier started shouting.

“These guys pulled up in the pickup truck, everyone was yelling back and forth at them,” Alter told the TV station.

Frazier, who reportedly lives about an hour south of Cincinnati in Georgetown, Ky., then hopped out of the truck, flipped off his hat and raised his fists. Alter took off his own hat and gestured at him, but he later told WCPO that he wasn’t trying to encourage a fight.

“I was more questioning him,” Alter told the station. “Like really, you want to fight?”

That’s when Frazier let loose, landing at least three punches to Alter’s face before another protester shoved him back toward his truck. An officer then quickly arrested him.

Alter, who said he was attending his first anti-Trump demonstration, told WCPO his first thought was, “What the hell? . . . He started just whaling on my head.”

Police also labeled Frazier as the aggressor. In a report obtained by WCPO, the arresting officer says he “exited the vehicle, stated ‘you want some,’ then struck the victim multiple times in the face.”

The man driving the red pickup truck was also handcuffed, but it’s not clear if he was charged with a crime.

As police led Frazier away from the scene, his arms secured behind his back, the crowd of protesters modified a favorite chant from Trump’s rallies.

“Lock him up!” they yelled.

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