A Legionnaires' disease cluster in the Harlem area of New York City has caused three deaths and over 70 people to be sickened. Here's what it is, symptoms and how it's spread.

Three people have died and at least 67 people have been diagnosed with Legionnaires’ disease in a cluster that broke out in New York City last week.

New York City officials gathered Thursday to address the growing concern regarding the cluster of Legionnaires’ disease cases in Central Harlem. As of Thursday afternoon, three people had died of the disease.