The attack, which unfolded in Friday near the neighbouring Emory University campus, prompted a massive law enforcement response to one of the nation's most prominent public health institutions, but no one else was reported to be injured.
Images shared by employees showed multiple CDC buildings with bullet-pocked windows, underscoring the breadth of the damage to a site where thousands of scientists and staff work on critical disease research.
The gunman was found on the second floor of a building across the street from the CDC campus and died at the scene, Atlanta Police Chief Darin Schierbaum said. He added that "we do not know at this time whether that was from officers or if it was self-inflicted".
The shooter was armed with a long gun, and authorities recovered three other firearms at the scene, according to a law enforcement official who spoke on the condition of anonymity because they were not authorised to discuss the ongoing investigation.
The gunman's motive is still unknown this early in the investigation, Atlanta Mayor Andre Dickens said.
Police declined to name the officer who was killed.
When the shooting kicked off, staff at a nearby restaurant hunkered down and said they heard a string of gunshots. "It sounded like fireworks going off, one right after the other," said Brandy Giraldo, the chief operating officer of The General Muir restaurant.
She then saw people running past her business. Two people paused to warn them of a shooter nearby.
When Anurag Mehta and his wife heard about the shooting, they tried to get to their three-year-old son in a preschool near the CDC, but they were unable to approach.
"I was thinking that when I left for work this morning, was that the last time I saw my son?" said Mehta, who later learned his son was safe.
The CDC and Emory's main campus are surrounded by affluent wooded neighbourhoods in northeast Atlanta. The area is hard to access, and notoriously traffic-choked, but on Friday few cars were in evidence as a warning siren blared.
Governor Brian Kemp praised the efforts of first responders.
"Twice this week, deranged criminals have targeted innocent Georgians," Kemp said, referring to the shooting at Fort Stewart as well as the CDC campus.
"Each time, brave first responders rushed toward the danger to subdue the shooter and save lives, reminding us of just how crucial they are."
