A lone gunman fired 500 shots at the Centers for Disease Control and Prevention (CDC) headquarters in Friday’s deadly shooting, officials revealed Tuesday. Georgia Bureau of Investigation officials said six CDC buildings were struck in the attack.

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.