Police used tear gas and flash-bang grenades Monday to halt a march against building an Atlanta-area police and firefighter training center that opponents call “Cop City.”

More than 400 people marched about 2 miles (3.2 kilometers) from a park to the site in suburban DeKalb County, chanting “stop Cop City” and “Viva, viva Tortuguita,” invoking the nickname of an activist who was fatally shot by state troopers while camping in the woods in protest earlier this year.

Georgia Attorney General Chris Carr. Courtesy photo Georgia Attorney General Chris Carr. Courtesy photo