The sources told NBC News and NBC station WDIV of Detroit that state Attorney General Bill Schuette will announce criminal charges against two employees of the state Department of Environmental Quality and one who works for the City of Flint.
The attorney general's office gave no official indication Tuesday what it would discuss at Wednesday's news conference, where it said Schuette would make a "significant announcement." Among those scheduled to be at the news conference are the Genesee County prosecutor and the chief investigators for the state's Flint water task force.
The development comes the same day that a federal judge dismissed a class action lawsuit filed by three Flint residents, ruling that the case is a state matter.
The plaintiffs are seeking $150 million in damages in behalf of about 31,000 Flint residents who paid their water bills and got lead-contaminated water in return. U.S. District Judge John Corbett O'Meara found that the residents had raised no federal issues, giving him no jurisdiction over their complaint.
Numerous members of Congress have called for Gov. Rick Snyder and Gina McCarthy, administrator of the U.S. Environmental Protection Agency, to resign over the crisis, which began after Flint switched its water source from Detroit's water system to the Flint River in 2014 to save money.
That water wasn't treated properly, and lead from aging pipes leaked into Flint homes and businesses. Elevated levels of lead — which have been linked to learning disabilities — have been found in local children's blood.
This story originally appeared on NBCNews.com.