Residents of Flint, Michigan, began getting gravely ill and in some cases dying in summer 2014 in one of the worst outbreaks of Legionnaires’ disease in US history, and a county health director says attempts to find the source were hampered when the state wouldn’t request federal assistance.

Genesee County Health director Jim Henry told CNN in an exclusive interview he believes deaths could have been prevented, but the health department could not get help from the state of Michigan or the Centers for Disease Control to find the source. Eventually, 87 people got Legionnaire’s and nine died.

Henry, who was a supervisor at the time of the outbreak, says state officials purposely kept the CDC away once the county wanted to look at the highly corrosive Flint River as the Legionnaire’s uptick began. The state had decided to switch the water supply source to the Flint River, and soon brown water began flowing from taps in the city.

Read the full story at cnn.com