July 7 (UPI) -- An outbreak of Legionnaires' disease in New York City's Upper East Side has sickened nearly two dozen people, officials said Tuesday, as they continue to investigate the cluster.

The community cluster has been identified in the neighborhoods of Carnegie Hill and Yorkville. The NYC Health Department said in a statement that there have been 23 cases of the disease, including 17 hospitalizations, since July 6.

The count is also an increase from 14 cases reported on Sunday. The cluster was first made public July 2 after two people were diagnosed with the disease.

City health officials are urging New Yorkers and those who have visited the areas since late June and are experiencing flu-like symptoms to contact a healthcare provider immediately.

"More than 100 NYC Health Department staff members have worked nonstop since the start of this cluster as we take aggressive action to ensure that we are cutting off the source of exposure as quickly as possible," Dr. Alister Martin, NYC health commissioner, said in a statement.