At least three people have died in a Legionnaires' disease outbreak in New York City, health officials confirmed, as authorities raced to identify the source of the bacterial contamination and prevent further spread. The deaths occurred over a short period, with fatality counts rising from one to three within roughly 24 hours of public reporting.

Legionnaires' disease is a severe form of pneumonia caused by the Legionella bacteria, which thrives in warm water systems including cooling towers, hot tubs, and large plumbing systems. The illness does not spread from person to person, but can sicken many individuals if a shared water source becomes contaminated. Elderly people, smokers, and those with weakened immune systems face the highest risk of serious illness or death.

New York City health officials launched an investigation to pinpoint the water source responsible for the outbreak. Authorities typically test cooling towers on rooftops of buildings and other water infrastructure in affected neighborhoods when clusters of cases emerge. The city has dealt with previous Legionnaires' outbreaks and has protocols in place requiring regular inspection and treatment of cooling towers.

Health officials urged anyone experiencing symptoms such as cough, fever, shortness of breath, or muscle aches — particularly those who may have been exposed to mist or spray from water systems in affected areas — to seek medical attention promptly. Early antibiotic treatment is effective against the disease if administered in time.