The Georgia Department of Public Health announced on Monday that the Sheraton Atlanta hosted “the largest recorded Legionella outbreak in Georgia.”

Georgia health department Director of Communications Nancy Nydam confirmed that at least one person has died as a result of the outbreak. The hotel has voluntarily closed “until the source of the Legionella is located and remediation is complete,” the department said in a statement.

Twelve lab-confirmed cases and 63 “probable” cases have been identified, all affecting those who stayed at the hotel between June 12 and July 15. Authorities also provided a brief description of the disease:

Legionella bacteria are found naturally in the environment, usually in fresh water. The bacteria grow best in warm water and can be found in shower heads and faucets, hot tubs, cooling towers, hot water tanks, decorative fountains or plumbing systems in large buildings. Legionnaires’ disease is a very serious type of pneumonia (lung infection) caused by Legionella bacteria. People can get Legionnaires’ disease when they breathe in small droplets of water in the air that contain Legionella.

In a statement released on Facebook, Sheraton Atlanta General Manager Ken Peduzzi said they are “working closely with the Georgia Department of Public Health, Fulton County Board of Health, and environmental experts to conduct testing to ensure there is no threat of Legionella infection.”

“A thorough cleaning of the hotel’s entire water distribution system has been completed as a precautionary measure,” Peduzzi said. “At this time, we are awaiting additional testing results and we will complete a review of those results, as will the Georgia Department of Public Health.”

The hotel will remain closed until at least August 14.