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.

Speaking to reporters on Tuesday, Georgia Bureau of Investigations Director Chris Hosey said 500 shell casings were recovered from the scene, while its believed 200 rounds hit six buildings in the CDC complex. Five firearms were also recovered, he said.

An Atlanta shooting that left a police officer dead may have resulted from the shooter’s skepticism about the COVID-19 vaccine, according to reports about the deceased gunman’s and past comments.