A fourth person has died in a Legionnaires' outbreak that's been linked to a hot tub display at a North Carolina state fair last month.

Nearly 150 people who attended the N.C. Mountain State Fair were sickened in addition to the four fatalities, according to an update Friday from the North Carolina Department of Health and Human Services. At least 133 people were diagnosed with Legionnaires' while another eight were confirmed to have a milder form of the disease called Pontiac fever.

At least 94 people were hospitalized in the North Carolina outbreak.

The fair took place between Sept. 6 and 15, and state health officials said the majority of people who got sick walked by hot tubs at the Davis Event Center during the second half of the fair.

Samples taken from the hot tubs on display tested negative for Legionella pneumophila, the bacteria associated with the disease, according to to Friday's report. The state's health department noted that environmental samples were not collected until two to three weeks after the fair's end, and might not be able to judge conditions while the festival was going on.

One sample from the women's restroom at the Davis Event Center did test positive for Legionella pneumophila, but scientists determined the strain was genetically different than the strain collected from patients.

The state's health department noted that testing was ongoing, but that hot tubs have previously been tied to Legionnaires' outbreaks around the world.

Legionnaires’ is a serious lung infection caused when bacteria called Legionella are spread through water droplets in the air and breathed in, according to the Centers for Disease Control and Prevention.

The disease can be treated with antibiotics, but about 1 in 10 people who are diagnosed with Legionnaires' dies, according to the CDC.

Symptoms of Legionnaires' can include coughing, muscle aches, fever, shortness of breath and headaches, the CDC says.