The city Health Department is investigating a cluster of Legionnaires' Disease that has popped up in Manhattan.

According to the Health Department, seven people have been diagnosed with the disease in the past 11 days in Lenox Hill.

The Health Department says one of those people died. They say that person was in their 90s and had additional health conditions that contributed to their death.

Four people are still recovering in the hospital, according to the Health Department, and two others were released from the hospital.

The city says it is testing water from cooling towers in the area.

Legionnaires' Disease is caused by a bacteria known as Legionella. Symptoms of the disease closely resemble the flu and include cough, fever, nausea and stomach discomfort.

Ben Kallos, the City Councilman who represents the area, was handing out fliers to warn people about the disease.

He says anyone feeling ill should get tested right away.

"If you've got that cough, if you've got a headache, if you got achy muscles, please seek immediate medical attention," Kallos said. "If you're elderly, if you are a person who has a compromised immune system, or if you're a heavy smoker, you are at increased risk."

Symptoms of the disease are similar to the flu and include cough, fever, nausea, and stomach discomfort.

The bacteria are not usually contagious — although they can possibly spread in rare cases — and can be treated with antibiotics.

The city health department has scheduled a public information session on Legionnaires' on Monday at 331 East 70th St. at 6:30 p.m.The Health Department says there are between 200 and 400 cases of Legionnaires' Disease in the city every year.

In 2015, there were multiple clusters of Legionnaires' disease in the Bronx. More than 100 people got sick and 12 died in the largest one, which was clustered in the South Bronx.