More disturbing news has come for residents of Flint, Mich., who are already reeling from an escalating health crisis tied to their city’s lead-contaminated water supply.

Michigan Department of Health and Human Services officials announced Wednesday that the city and the surrounding area have seen a spike in cases of Legionnaires’ disease — a bacterial infection that can be deadly for between 5 to 30 percent of those who contract it.

So far, 87 cases have been diagnosed since June, two months after Flint changed its water source to the Flint River, the Detroit Free Press reported. Ten of those cases were fatal.

The city’s switch in water supply has been blamed for discolored and strange-smelling water and elevated lead levels in children’s blood. In December, a state task force found that Flint violated rules requiring that it treat water to avoid the pipe corrosion problems that helped make the water toxic, and city, state and county officials are now being accused of a coverup by researchers who believe authorities knew about the health threat to Flint citizens but did nothing to protect them from it.

Flint reconnected to Detroit’s water system in October after doctors at a local medical center sounded the alarm about the dangerous lead levels.

On Wednesday, state officials said they couldn’t make a direct link between the water supply and the spike in Legionnaires’ cases — which is significantly higher than in the past, when Genesee County had a maximum of 13 cases a year. Some of the cases were reported in the area surrounding the city, which uses a different water system.

But Gov. Rick Snyder (R) said at a news conference, according to Michigan Live, that the Legionnaires’ cases “just added to the disaster we were already facing.”

Marc Edwards, who heads the Virginia Tech research team that helped expose the city’s lead problem, told the Free Press that there was a “very strong likelihood” that the new water supply is linked to the increased rate of the disease.

“Our hypothesis is that something about the Flint River and lack of corrosion control, plus big buildings, is creating these problems,” he said.

On Wednesday night, the Associated Press reported that the Centers for Disease Control and Prevention are consulting with local health officials about the Legionnaires’ outbreak, though the agency has no plans to send staff to Flint.

The Legionella bacteria, discovered in 1977 after more than 200 people were sickened after an American Legion conference the previous summer, dwells in warm water like that found in fountains, hot tubs, the cooling towers of large buildings and, sometimes, plumbing systems.

When it sickens people, which happens between 8,000 and 18,000 times a year in the United States, according to the CDC, it tends to cause a raging pneumonia-like respiratory disease. Victims will experience high fevers, muscle aches and trouble breathing. People with weakened lungs or immune systems — the elderly, smokers, those who are already ill — may experience lung failure or even die.

Last summer, a Legionnaires’ outbreak in New York killed 12 people and sickened more than 100 others. The Legionella bacteria was eventually traced back to the cooling tower of a Bronx hotel, according to the Associated Press.

Officials with the Michigan Department of Health and Human Services said they first noticed the increase in Legionnaires’ diagnoses in the fall of 2014, according to the Free Press. The following April they began interviewing affected residents.

This past summer, Edwards and his team — who were already investigating the city’s water supply — noticed that the older plumbing systems of some of Flint’s large buildings had high levels of the Legionella bacteria.

At the press conference Wednesday, authorities said that the announcement about Legionnaires’ doesn’t change their advice for residents, who are currently drinking bottled water distributed by the National Guard.

Residents can still bathe and shower in city water, Chief Medical Executive Erin Wells said, according to Michigan Live. Lead is usually absorbed into the body through ingestion (drinking contaminated water) or inhalation (breathing in the dust of degrading lead paint), rather than through the skin. Likewise, people become infected with Legionnaires’ by inhaling contaminated water particles; it can’t be transmitted from one person to another and is not absorbed through the skin.

Speaking to the Free Press, Edward assured that there’s every reason to believe that the bacteria no longer a threat to residents.

Forty percent of people in Flint, a city about 70 miles north of Detroit, live below the poverty line, according to U.S. Census data. Residents told The Washington Post Wednesday that the water crisis has strained an already-stricken city. They say they felt betrayed by the sluggish response from officials who downplayed concerns about the water supply for more than a year, even as the city has been in violation of the federal Safe Drinking Water Act for the past year.

“This is very hard on people. Really hard,” said Christine Brown, 55. Brown has been unemployed since she was laid off from her city job in 2008, and she said she can only drive in to pick up clean water on days when she can afford the gas.

Speaking to reporters Wednesday, Snyder welcomed the federal investigation into Michigan authorities’ handling of the crisis, adding that a good portion of the fault “could lie” with the Michigan Department of Environmental Quality, according to the Free Press.

“We’re taking every action within reason, and going beyond reason to address this,” he said, adding, “This is something you wish that never happened, and let’s see that it never happens again in the state of Michigan.”