The Centers for Disease Control and Prevention told staff it expects them to return to offices by Sept. 15, roughly five weeks after a gunman’s deadly attack on the agency’s headquarters in Atlanta, CNBC has learned. 

“Your safety remains our top priority. We are taking necessary steps to restore our workplace and will return to regular on-site operations no later than Monday, September 15,” Lynda Chapman, the agency’s new chief operating officer, said in an email sent Thursday that was viewed by CNBC.

Chapman said all staff will be expected to return to their offices by that date, according to the email. For employees whose workspaces remain impacted by the shooting — including physical damage from the gunman’s attack — the CDC will provide alternative spaces on its campus, Chapman wrote in the email. 

She said the agency has made “significant progress” on repairs at the CDC Roybal Campus in Atlanta. CDC leadership and a “Response and Recovery Management” team are working to address staff concerns and ensure a safe environment as the agency transitions back to in-office work, Chapman added. 

CDC staff had been instructed to work remotely following the Aug. 8 shooting, with options to return to the office in the weeks that followed, according to two people familiar with the matter, who requested anonymity for fear of retribution for speaking to the media.

The Department of Health and Human Services did not immediately respond to a request for comment.

The internal announcement comes at a tumultuous time for the CDC and its workforce. The shooting didn’t result in injuries among CDC staff but shell-shocked a workforce that was already reeling from sweeping changes under HHS Secretary Robert F. Kennedy Jr., including staff cuts and heated controversy over his efforts to change CDC immunization policies and fire the agency’s panel of vaccine advisors.

The return-to-office guidance also comes as the CDC grapples with a leadership upheaval: The White House earlier this week said President Donald Trump had fired the agency’s director, Susan Monarez. Four other top officials resigned, some of them citing the politicization of the agency and a threat to public health.  

Authorities identified the gunman behind the shooting at CDC headquarters as Patrick Joseph White and said they recovered five guns and more than 500 shell casings from the scene. During the attack, agency employees were forced to barricade themselves in offices.

White fatally shot a responding police officer, 33-year-old David Rose, and then killed himself. White had blamed the Covid-19 vaccine for making him depressed and suicidal. 

Before her firing, Monarez appeared to directly blame the role of misinformation in the shooting, according to an email sent to staff on Aug. 12 that was viewed by CNBC.

In the note, Monarez said, “the dangers of misinformation and its promulgation has now led to deadly consequences. I will work to restore trust in public health to those who have lost it- through science, evidence, and clarity of purpose. I will need your help.”