The children's hospital first became aware of the mold problem when patients who had surgeries in March and April of a year ago developed infections, Del Beccaro said.
On Wednesday, the hospital confirmed to Fox News that one patient was dead because of potentially risky mold.
Bernal said those who became ill were more susceptible to infection due to the procedures they had done at the hospital.
"We are deeply saddened that one of our patients died after developing an Aspergillus infection in 2018", Seattle Children's public relations manager Alyse Bernal told CBS News Tuesday in a written statement.
On May 18, the hospital closed four operating rooms where mold had been detected, continuing to perform some procedures in other areas, according to the hospital.
The ORs have been infested - on and off - for about a year, likely because of deficiencies in air-handling and purification systems, the hospital said. Maintaining a safe environment for our patients is our highest priority and over the course of the past six weeks we worked diligently to implement extensive improvements and corrective actions so that we can safely reopen our operating rooms.
The hospital hasn't determined when that will be.
The Seattle Times reports about 1,000 surgeries have been postponed, while other surgeries have been moved to other hospitals. On May 24, the hospital contacted patients and families who had surgery on the main campus in the previous four months to alert them of possible exposure to Aspergillus and of the symptoms. But people with lung disease or weakened immune systems, and especially organ or stem-cell-transplant patients, are at higher risk of developing aspergillosis, a disease caused by the mold. Most surgeries have been moved to Harborview Medical Center, University of Washington Medical Center, Swedish Medical Center and Mary Bridge Children's Hospital in Tacoma.
"Both hospitals are working with Seattle Children's to make sure that they do what they can do to help them", Mankowski said.
The hospital said it is deep cleaning the rooms and replacing equipment for air purification and humidification.
She said the hospital is correcting the issues. Mold spores floating in the air can get into bodies opened up for surgery, then slowly turn into an infection once the wound is closed, he added.
Children's also reached out to Public Health - Seattle & King County, which connected the hospital to the CDC because the federal agency had more expertise dealing with that kind of mold, public health spokesperson James Apa said. Washington state Department of Health (DOH) investigators also checked out the hospital and offered suggestions on how to improve air quality, which the hospital followed, Bernal wrote. The operating rooms were initially shut down on May 18, after air tests detected a potentially unsafe fungus known as Aspergillus. She would not say whether mold was detected in those rooms. The remaining 10 were closed six days later.