Officials are still investigating a shooting at the Centers for Disease Control and Prevention headquarters in Atlanta, Georgia, that killed a police officer on Aug. 8. The suspect, Patrick Joseph White, 30, may have been disgruntled over vaccine side effects before perpetrating the shooting, according to multiple reports.

The U.S. CDC has tightened security following an attack Friday on its Atlanta headquarters that left a police officer and the gunman dead, including having employees work from home on Monday and removing vehicle decals showing where they work.

Police in Atlanta say the suspect is dead after a shooting near Emory University and the Centers for Disease Control and Prevention headquarters.