The director of Michigan's Department of Health and Human Services, Nick Lyon, has been charged with involuntary manslaughter and misconduct in office over the Flint water crisis. Both are felonies in Michigan.

The state's chief medical executive, Dr. Eden Wells, will be charged with obstruction of justice. Four other officials, including the former Flint emergency manager and former director of public works, were also charged with involuntary manslaughter.

Lyon and Wells are the highest-ranking state officials to be charged in the crisis. The charges stem from an investigation led by Michigan's attorney general.

"Mr. Lyon failed in his responsibilities to protect the health and safety of the citizens of Flint," Michigan's Attorney General Bill Schuette said at a press conference Wednesday.

"The families of Flint have experienced a tragic, tragic health and safety crisis for the past three years," he said.

The involuntary manslaughter charge stems from an outbreak of Legionnaires' disease, a type of pneumonia, that spread in the city following its switch in water source. According to the indictment, Lyon knew about the outbreak but failed to alert the public. The disease killed 12 people and sickened more than 70 in 2014 and 2015, according to MLive.

Flint's water quality attracted national attention after lead seeped into the city's pipes. The city had switched its water source to the Flint River and failed to immediately treat it. Officials dismissed residents' concerns that the water was discolored and smelled.

Residents were forced to use either contaminated or bottled water.

The state's culpability is rooted in the fact that Flint was being run by state-appointed emergency managers at the time of the water crisis. Many say that state officials, therefore, were responsible for the health and safety of the city.

The state officials involved have contended that because the outbreak was contained to one county, the county health department held ultimate responsibility.

Schuette launched a probe of the water crisis in January 2016. The investigation is looking into "what, if any, Michigan laws were violated in the process that resulted in the contamination crisis currently forcing Flint residents to rely on bottled water for drinking, cooking and bathing as they fear for their health."

Former Flint Director of Public Works Howard Croft, one of the officials charged with involuntary manslaughter, maintains he is innocent. In a statement, his lawyer said Croft "continues to maintain his innocence on this forthcoming charge and the charges previously brought against him" and that he will be vindicated as more facts about the water crisis come to light.

In response to the charges, Rep. Dan Kildee, who was born and raised in Flint and now represents the district that includes it, said he supports the investigation and its attempt to "hold everyone accountable who did this to Flint."

"The state and the Governor created this crisis and they must do more to help Flint's recovery," Kildee said in a statement.

Copyright 2017 NPR. To see more, visit http://www.npr.org/.