ValdostaStudent demonstrators who walked on an American flag to protest racism have sparked a counter movement, prompting a south Georgia university to cancel classes Friday ahead of a rally expected to draw large crowds of flag supporters to Valdosta.

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Valdosta State University found itself in the center of a controversy after a video shared on social media showed an Air Force veteran, Michelle Manhart, taking an American flag away from demonstrators who had walked on it to protest racism. At the protest, held a week ago, Manhart was detained by police when she refused to return the flag. She later was banned from the campus of 11,500 students. She was not a student at Valdosta State, according to the school.

Video of the incident:

The flag-walking demonstration involved three protesters, university spokesman Andy Clark said.

Flag supporters planned a rally for Friday afternoon.

Meanwhile, tensions were heightened at Valdosta State when campus police found a backpack containing a handgun Tuesday. Police said they traced the gun to a protester who was part of the flag-walking demonstration, and they issued a warrant for Eric Sheppard’s arrest on charges of bringing a firearm onto a college campus. Sheppard fled and has not been found by authorities, Clark said.

But university administrators said it was the possibility of thousands of people rallying on the outskirts of campus Friday that ultimately led to the decision to give students a day off.

“That level of traffic and that many people will disrupt a lot of things in the city,” Clark said. “We’re from an overall safety perspective looking to close the campus down today so they can have a peaceful rally.”

Organizers of the “Flags Over VSU” rally said they expected as many as 4,000 people Friday afternoon, WALB-TV reported. University administrators arranged for extra police to be on campus to provide security during the rally, Clark told The Valdosta Daily Times.

University administrators faced a backlash on social media after Manhart was issued a criminal trespass warning, essentially banning her from campus. Critics saw the university siding with demonstrators who walked on the flag over a military veteran trying to save it.

“We were protecting their right to free speech and civil liberties” without taking sides, Clark said.