The Georgia man accused of firing more than 500 shots at the CDC headquarters aimed to publicize his opposition to COVID-19 vaccines, authorities said Tuesday.

CDC security guards stopped White from driving into the campus on Friday before he parked near a pharmacy across the street and opened fire from a sidewalk. The bullets pierced “blast-resistant” windows across the campus, pinning employees down during the barrage. More than 500 shell casings were recovered, the GBI said.

Speaking to reporters on Tuesday, Georgia Bureau of Investigations Director Chris Hosey said 500 shell casings were recovered from the scene, while its believed 200 rounds hit six buildings in the CDC complex. Five firearms were also recovered, he said.