Documents found in a search of the home where Patrick Joseph White lived with his parents “expressed the shooter’s discontent with the COVID-19 vaccinations,” authorities said.

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.

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.