Four cases of Legionnaires' disease have been confirmed in Lowell, Massachusetts.
The Lowell Department of Public Health said the cases in that city are not related to the outbreak in Hampton, New Hampshire, in which 15 people were diagnosed with the illness and one was killed.
While it is not known if the four Lowell cases are connected to each other, city health officials say the public is not believed to be at risk.
The current weather conditions support the growth of the Legionella bacteria that causes the illness, according to the Massachusetts Department of Public Health.
Legionnaires' disease is bacterial pneumonia spread by inhaling droplets of water contaminated with the bacteria.
In New Hampshire, multiple hot tub spas have been closed as a precaution while health officials investigate what caused the Hampton outbreak.