New York City officials said they are investigating a cluster of Legionnaires' disease that has caused one death and nearly two dozen illnesses.

At least 22 people have fallen ill, including one person who has died, from Legionnaires’ disease in New York City over the last two weeks, according to the city’s health department. City health officials believe that the people most likely became ill after breathing in bacteria sprayed from a cooling tower in central Harlem.

Legionnaires' disease can be fatal, especially for older adults, smokers and those with weakened immune systems.