The suspect in the shooting targeting the Centers for Disease Control and Prevention had letters that showed his “discontent” with COVID-19 vaccines.

Authorities said Tuesday that investigators recovered at least 500 shell casings at the scene, estimating that White fired more than 180 shots at the CDC headquarters using his father’s long gun. White shot and killed himself at the scene before responding officers could reach him.

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.