The New York City Health Department is looking into three cases of Legionnaires' disease in the Bronx.

The investigation centers on a group of connected buildings — 100, 120, and 140 Carver Loop — at Co-Op City.

Residents were notified by a flyer earlier this week of the disease that originated from three separate buildings that share a hot water supply. One elderly resident succumbed front the disease that's contracted by breathing in water vapor that contains Legionella bacteria.

The disease is caused by breathing in water vapor that contains Legionella bacteria.

The health department is taking samples from the complex's internal plumbing systems.

In the meantime, it's advising older residents or those with medical conditions to take baths rather than showers until the investigation is complete.

"The main message is to avoid water mist, and the most common place to encounter water mist in an apartment is the shower," Health Commissioner Dr. Mary Bassett said. "Legionnaires' disease causes pneumonia — it's a form of pneumonia — and in people who are older pneumonia can be a very serious disease."

Health officials also warning anyone experiencing flu-like symptoms to get tested for the disease immediately, and to stay vigilant.

"I have to tell the people in the building here, filter your water, be sure about what you drink," one man said outside one of the buildings.

We are told the three cases took place in the last 12 months. But despite the warnings, officials are advising tenants that the drinking water is safe. They expect to have the results of the water tests back in two weeks.

Each year, there are 200 to 500 cases of Legionnaires' disease reported in the city.