The gunman who opened fire Friday at the US Centers for Disease Control and Prevention broke into his father’s safe to get the five firearms recovered at the scene, state investigators said Tuesday, as some CDC workers seeking answers and reassurance from leadership were left dissatisfied by a short agency-wide meeting about the shooting.

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 man who attacked the CDC headquarters in Atlanta on Friday fired more than 180 shots into the campus and broke about 150 windows