Two Brooke Army Medical Center staff members tested positive for bacteria linked to the fast-spreading type of pneumonia known as Legionnaires’ disease, the San Antonio Current in Texas reported.

The two staff members work in an administrative building, not the medical center’s hospital, according to the report, and workers in the building have been relocated.

The two cases qualify as an “outbreak,” BAMC officials said in a news release. 

Legionella bacteria is rarely passed between people, and more often contracted from a source in the environment, such as a building with a contaminated water system, for example, and when people inhale contaminated mist or vapor, 

In the most recent large outbreak of Legionnaires’ disease, 12 people died in New York City in 2015, according to The New York Times.

[From the CDC: Are you at risk for Legionnaires’ Disease?]