Confederate flag supporters rallied at a Georgia park in what was one of the largest pro-flag rallies since the Charleston, South Carolina, shooting. Above, supporters argue their position after the Confederate battle flag was permanently removed from the South Carolina statehouse grounds during a ceremony in Columbia, South Carolina, July 10, 2015. Reuters/Jason Miczek

Hundreds of people flooded Georgia’s Stone Mountain Park Saturday in what might be the largest pro-Confederate flag rally since a mass shooting at a black church in Charleston, South Carolina, brought renewed criticism of the Civil War-era symbol. Cruising up in pickup trucks and proudly waving rebel flags, demonstrators insisted the event would be peaceful, and they were rallying to support “heritage, not hate,” the Atlanta Journal-Constitution reported. The newspaper said the rally was organized by J.T. Nicholson of Thomaston, Georgia, who started a Facebook page that quickly garnered more than 6,000 likes.

In advance of the rally, organizers posted rules of conduct online: Drinking alcohol, engaging in violence and uttering racial slurs are among the prohibited activities.

“Remember there will be people everywhere,” the organizers wrote. “Possibly media and cameras, ONE piece of negativity and that will be what goes viral and that is what we will be remembered for.”

WSB-TV, Atlanta, tweeted a photo of attendees in camouflage carrying what looked like rifles.

The Southern Poverty Law Center, which tracks hate group activity, said via Twitter Saturday there have been 132 pro-Confederate flag rallies since Dylann Roof, a white supremacist, opened fire at Emanuel African Methodist Episcopal Church and killed nine people. The group said Saturday’s rally could be the largest yet.

The rally, according to the event’s Facebook page, is planned to continue until 11 p.m. More than 1,000 people RSVP’d to attend. The Journal-Constitution put the headcount at “several hundred” as of late Saturday morning and said traffic on Interstate 285 and U.S. 78 was backed up for miles. By early afternoon “Stone Mountain” was trending on Twitter.

Stone Mountain Park, about 25 miles east of Atlanta, is home to a massive Confederate memorial and was the site of the second founding of the Ku Klux Klan in 1915.

Christopher Zara is a senior writer who covers media and culture. News tips? Email me. Follow me on Twitter @christopherzara.