But the shower wouldn’t start, and warning lights appeared as a cascading series of safety systems began to fail inside one of the world’s most advanced biosafety level 4 labs. That's the highest level of containment and security, reserved for work with deadly Ebola and smallpox viruses and other pathogens that lack vaccines or reliable treatments.

The gasket seal around the exit door to the changing room deflated to the point that the scientists could see light coming in. And as they held that door shut and started an emergency chemical deluge, things got even worse.

The shower's door back into the infectious disease lab "forcefully" burst open again and again – and they couldn't even hold it shut. Meanwhile, air pressure alarms were blinking and monitors displayed the lab as "red," according to records of the February 2009 incident recently obtained by USA TODAY under a Freedom of Information Act. The CDC took 3 ½ years to fulfill the request.

The records release comes as the CDC has faced two congressional hearings since a series of high-profile lab incidents in 2014 with anthrax, Ebola and a deadly strain of avian flu, and amid mounting concerns in Congress about the effectiveness of lab regulation and whether a lack of transparency keeps serious lab safety problems hidden from the public.

Despite the dramatic series of equipment failures in the 2009 CDC biosafety level 4 (BSL-4) lab incident, the newly released records include emails showing some within the agency sought at the time to avoid reporting to federal lab regulators in another division at the agency, though they eventually were notified.

“The incident summary reads like a screenplay for a disaster movie,” said Richard Ebright, a Rutgers University biosafety expert who reviewed the report at USA TODAY’s request and called it a major incident.

“Overall, the incident shows that failures — even cascading, compounding, catastrophic failures of BSL-4 biocontainment labs occur,” said Ebright, who has testified before Congress about CDC safety issues. “And the attempted cover-up within the CDC makes it clear that the CDC cannot be relied upon to police its own, much less other institutions.”

CDC officials say there was never any risk posed by the lab’s equipment failures. Although the scientific team just finished conducting an inventory of a freezer in the lab that contained numerous frozen virus specimens — likely including Ebola and smallpox viruses, no work with live agents had yet been done in the lab, which was still new at the time.

CDC's Building 18 houses numerous labs, including a suite of biosafety level 4 labs. Documents released under the Freedom of Information Act reveal a dramatic 2009 incident in a decontamination chamber in one of the BSL-4 labs.

After the four scientists called for help, building engineers were able to operate the chemical shower manually, allowing for a safe exit from the lab, the CDC said. The failures were traced to a software error in the lab’s operating system and it was fixed the same day. Additional alarms were added to the lab to notify engineering staff if such a malfunction were to occur again, which it hasn’t, the agency said.

“Yes, there was some malfunction, but there was a clearly established protocol for how to deal with the malfunction and that was quickly and rapidly executed," said Steve Monroe, who last fall was permanently appointed to head a new CDC lab safety office charged with improving the safety culture at the Atlanta-based agency. Even if work with live pathogens had been underway inside the lab, he said, “the potential risk would have been exceedingly small.”

Last month, USA TODAY revealed that a subset of labs at the CDC's Fort Collins, Colo., infectious disease facility are among a handful of labs nationwide that have had their federal permits secretly suspended in recent years for serious safety violations while working with bioterror pathogens.

Yet USA TODAY has now learned that CDC kept even Congress in the dark about the Fort Collins incident and some others — despite an oversight committee asking the agency in 2014 for a list all incidents at CDC labs since 2002 involving bioterror pathogens found in unauthorized areas. The CDC says the information was “inadvertently omitted.”

According to an August 2014 letter CDC Director Tom Frieden sent to the chairman of the House Energy and Commerce Committee, recently obtained by USA TODAY, the CDC did not include the Fort Collins incident when it responded to the committee's questions in the wake of a hearing that summer on CDC safety lapses. The letter listed 10 other incidents, but not the incident involving specimens of Japanese encephalitis virus found in an unauthorized CDC lab in Fort Collins. Although the virus was considered a "select agent" — the government's term for certain viruses, bacteria and toxins that have the potential to be used as bioweapons — at the time of the incident, it was delisted in 2012.

“We’re very concerned that there could be some gaps in CDC’s responses to our pointed oversight inquiries,” U.S. Rep. Fred Upton, R-Mich., the committee’s chairman, told USA TODAY.

In response to new questions from the committee, Monroe said the CDC has identified “a handful” of other incidents that also were not disclosed in Frieden’s 2014 letter, which was sent before his new safety office had created a centralized reporting system for lab accidents and “near-miss” incidents at the agency.

“Because we don’t want to repeat having omitted any data we supplied to the committee, we are working extensively to make sure we have an absolutely comprehensive answer before we reply to the committee,” Monroe said.

Monroe said his office is committed to being as open and transparent as possible about lab incidents at CDC, and pointed to the agency's public announcement in March disclosing that a CDC lab worker had become infected with a strain of salmonella used in their work.

Yet getting the CDC to release records about lab incidents under the federal Freedom of Information Act (FOIA) can often take several years.

In January 2015, in an effort to determine the extent of lab accidents at the agency's facilities, USA TODAY filed a FOIA request seeking copies of all incident reports at CDC labs in Atlanta and Fort Collins during 2013 and 2014. The CDC granted the request "expedited" processing status because USA TODAY demonstrated a compelling public need for the information. But the agency has said it will likely be 2018 before the records are released.

The newly disclosed 2009 incident in the BSL-4 decontamination shower is among about 4,000 pages of records the agency released in late January  in response to two FOIA requests USA TODAY filed in June 2012. Those requests sought records about airflow and security door incidents at CDC’s $214 million, 368,000-square-foot  Emerging Infectious Diseases Laboratory in Atlanta, commonly referred to by the agency as Building 18.

Most of these released records — which focus on airflow engineering issues in labs — involve a 2012 incident that USA TODAY reported four years ago based on documents obtained from sources. The issue involved air from inside a potentially contaminated lab briefly blowing outward into a "clean" corridor where a group of visitors weren't wearing any protective gear. Among other incidents revealed in the records:

  • In 2011, a worker feeding animals in an enhanced biosafety level 3 lab used for studies on dangerous strains of avian flu, was unable to shower out of the lab after a construction contractor mistakenly closed the wrong water valve in a service tunnel. Not knowing when the water would come back on, the worker removed her protective equipment, put on a clean protective suit and left the lab without taking a shower. "I escorted her through the service tunnel to building (redacted) where she signed into our (redacted) select agent laboratory. She disposed of the tyvek suit in a biohazard bag, placed her scrubs in the laundry bin, and took a personal shower." The CDC told USA TODAY that because the potential for any exposure was considered low risk, a medical evaluation was not required.
  • In 2008 an unvaccinated repair worker was potentially exposed to an undisclosed pathogen when a door containing contaminated items unexpectedly opened in a malfunctioning device, called an autoclave, that is used to sterilize equipment and other items. The infectious materials inside the device included bedding from infected mice and used laundry.  While a report of the incident said that any material that may have escaped through the clean-side door that opened "was likely to be drawn upward toward the exhaust," the worker was told to shower and his clothes, shoes, wallet, watch and other personal items were disinfected. He was escorted to the clinic for evaluation. The report notes that the autoclave "was installed backwards during building construction" and that as a result, the manual override controls for doors are reversed "which ultimately resulted in the incident."

Building 18, which opened in 2005 has had a series of significant issues over the years. While the building's many other high-containment and lower security labs were in operation from the start, its suite of BSL-4 labs did not go "hot" and start working with pathogens until around early 2009. The lab complex made news in 2007 when backup generators didn’t work to keep airflow systems working during a power outage and in 2008 for high-containment lab door that was being sealed with duct tape. The duct tape was applied after a 2007 incident where the building’s ventilation system malfunctioned and pulled potentially contaminated air out of the lab and into a “clean” hallway. Nine CDC workers were tested for potential exposure to Q fever bacteria. None were infected.

Read all the records released by CDC in response to USA TODAY's 2012 Freedom of Information Act requests here and here.

For full coverage of USA TODAY's ongoing investigation of safety and security issues in biolabs across the country, go to: biolabs.usatoday.com

Follow investigative reporter Alison Young on Twitter: @alisonannyoung