New York City's Department of Health is tracking an outbreak of Legionnaires' disease on the Upper East Side of Manhattan.

Health officials said 23 people have contracted the pneumonia-like illness in the neighborhoods of Carnegie Hill and Yorkville as of July 6, with 17 hospitalizations reported and no deaths thus far.

The outbreak has prompted an aggressive investigation into cooling towers in the affected area, while officials stressed there is no evidence the city's drinking water or residential plumbing systems are to blame.

According to the New York City Department of Health, the cluster is centered in three ZIP codes.

Residents can continue to drink tap water, shower, cook, and use home air conditioners safely, the agency said.

The city is urging anyone who lives, works, or recently visited the area and is experiencing flu-like symptoms — including cough, fever, or difficulty breathing — to seek medical attention immediately.

Legionnaires' disease is treatable with antibiotics but can become severe or fatal if left untreated, particularly for older adults, smokers, and people with weakened immune systems.

The New York Post reported that several patients remain hospitalized, with some in intensive care units.

Health Commissioner Dr. Alister Martin said the city is still in the early stages of the investigation but confirmed at least one patient has already been discharged after recovering from the illness.

Officials believe the outbreak is most likely linked to a contaminated cooling tower rather than a building's plumbing system.

The Health Department has begun testing roughly 160 cooling towers across the Upper East Side and says remediation efforts are already underway while investigators work to identify the source.

"We're pretty confident that this is coming from a cooling tower," Martin said during a virtual town hall, according to the Post. "Your water is safe. Your air conditioners are safe."

Legionnaires' disease is caused by Legionella bacteria, which can grow in warm water systems.

People become infected by inhaling contaminated water vapor or mist, not through person-to-person contact or by drinking tap water, according to city health officials.

The outbreak has renewed attention on New York City's cooling tower regulations, which were strengthened after previous Legionnaires' outbreaks, including a deadly Bronx outbreak in 2015 and another cluster in Harlem last year.

Building owners are required to routinely inspect and test cooling towers for Legionella bacteria.

City Council Speaker Julie Menin called for a review of compliance with the updated rules, saying officials should determine whether affected buildings followed the testing requirements that took effect earlier this year.

Health officials emphasized that the risk to the general public remains low but urged anyone with symptoms to seek prompt medical care, noting that early diagnosis and treatment significantly improve outcomes.