Officer Mark Morgan of Emory University Police fired at gunman Patrick Joseph White during the shooting at the CDC campus.

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 Bureau of Investigation identified the gunman as 30-year-old Patrick Joseph White, of Kennesaw, Georgia.