ALBANY, N.Y. (AP) — A fourth person has died amid an outbreak of Legionnaires’ disease at an assisted living facility in upstate New York, health officials said Tuesday.

Albany County officials announced the initial three deaths last week, among ten people who tested positive for the disease at Peregrine Senior Living at Shaker in Albany.

Albany County Department of Health Commissioner Maribeth Miller said in a prepared statement Tuesday that there were two new positive tests for legionella, the bacteria that causes Legionnaires’ disease, and now a total of four deaths connected to the outbreak.

Legionnaires’ disease is a severe type of pneumonia caused by inhaling small water droplets containing Legionella bacteria, which can lurk inside plumbing systems. People who are older, have weakened immune systems or have certain medical conditions like chronic lung disease are at higher risk for developing Legionnaires’ disease.

County officials said last week that two of the people who died had been hospitalized for other health issues, meaning it was unclear whether Legionnaires’ disease had killed them. Miller in her prepared statement Tuesday said there were four “pneumonia fatalities in connection with this outbreak.” County officials would not elaborate.

In response to the outbreak, health officials have been working with Peregrine and area hospitals to make sure that people with symptoms are tested and treated and a water treatment program is implemented. Water restrictions have been in effect, Miller said, and .

Peregrine’s operators said last week that they were coordinating with state and local health officials to safeguard residents, staff and visitors. An email seeking additional comment was sent Tuesday to operators of the facility.