The city health department is looking into the cause of at least a dozen cases of Legionnaires' disease in Queens.

Officials said Tuesday that the first case popped up two weeks ago in downtown Flushing.

The 12 people sickened range in age from early 30s to late 80s, but most are over 50. All were hospitalized and had serious underlying health conditions, according to the health department.

Seven people have been discharged, but all are said to be doing well, officials said.

The health department is evaluating two more possible cases.

The cooling towers in the area are being looked at as a possible source and have been tested for Legionella, the bacteria that cause Legionnaires' disease.

"We will soon have results on those samples — preliminary results — and we will take action on those results immediately," said Dr. Demetre Daskalakis, the deputy health commissioner for the Division of Disease Control. "Those actions will mean increasing chemicals within the cooling towers to make sure that if there are any bacteria that we are actually killing them."

Officials said any cooling towers found to have any living bacteria will have to be drained and disinfected.

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

Officials said there is no risk to drinking water sources, but they advise anyone exhibiting the symptoms to seek medical help immediately.

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

The health department said there are between 200 and 400 cases of Legionnaires' disease in the city every year.

Earlier this year, one person died and several others were sickened when a Legionnaires' cluster broke out on the Upper East Side.

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.

In response to the deadly outbreak of Legionnaires' two years ago, the city adopted new guidelines, requiring building owners to register their cooling towers, which would be inspected and tested on a regular basis.

We're told that the vast majority of towers in the area are in compliance, but since the cluster has to come light, they have found a number of towers not on that registry.