A Texas man who wore a hat supporting former President Donald Trump punched an election worker who told him that wearing items endorsing a candidate are prohibited at voting sites, a sheriff said Friday.

The election worker, identified as a 69-year-old man, was treated at the scene Thursday and returned to his election post at a San Antonio library on Friday, officials said. The suspect was arrested on felony charges of assaulting an elderly person and could face additional charges, Bexar County Sheriff Javier Salazar said.

The alleged assault happened at the end of the first week of early voting in Texas, where long lines have stretched outside some polling places.

Both the sheriff and county elections administrator urged voters to stay calm and patient during sometimes long waits to vote during what they described as a contentious election.

“Thankfully there was nothing life-threatening about what occurred, but it was still an ugly incident,” Salazar said.

The suspect, identified as Jesse Lutzenberger, remained in jail Friday evening, according to Bexar County records. Jail records did not list an attorney and a phone number for Lutzenberger’s home could not immediately be found Friday.

Under Texas law, wearing clothing for or against a candidate inside a polling place is prohibited, as it’s considered electioneering. Lutzenberger allegedly entered the polling location in a red “MAGA or TRUMP” baseball cap, according to an arrest affidavit.

After being told he had to remove his cap in the voting area, Lutzenberger did and proceeded to cast a ballot, according to Salazar. He then put the cap back on before leaving, followed by the clerk again telling him remove the hat while inside the building.

As the clerk escorted him out of the library, Lutzenberger allegedly threw an elbow or arm back toward the clerk and then turned to punch him in the face multiple times, according to Salazar.

The clerk was treated at the scene by emergency medical personnel, Bexar County Elections Administrator Jacque Callanen said.

Salazar said there have been “several” incidents of voters wearing prohibited clothing or caps into polling places, but they then removed them when the state law was explained to them.

“Nothing here is worth getting hurt for, going to jail for,” he said.