Two state regulators and a city employee have been charged with official misconduct, evidence-tampering and other offences over contaminated water supplies in Flint, Michigan.
The Flint water crisis, which saw the city's water supply contaminated with high levels of lead, has alarmed the US and led to claims of racism.
For nearly 18 months, the poor, mostly black city of 100,000 used the Flint River for tap water as a way to save money - a decision made by a state-appointed emergency manager - while a new pipeline was under construction.
But the water was not treated to control corrosion, which meant lead was released from ageing pipes and fixtures as water flowed into homes and businesses.
Governor Rick Snyder failed to acknowledge the problem until last autumn when tests revealed high levels of lead in children, in whom the heavy metal can cause low IQs and behavioural problems.
The crisis - and state officials' slow and dismissive response to complaints about the water from experts and Flint residents - led to allegations of environmental racism, emerged as an issue in the presidential race during Michigan's Democratic primary in March, and sent other cities around the US rushing to test their water.
"This is a road back to restoring faith and confidence in all Michigan families in their government," Michigan Attorney General Bill Schuette said.
He warned there will be more charges and added: "No one is off the table."
Michael Prysby, a district engineer with the state Department of Environmental Quality, and Stephen Busch, a supervisor in the department's drinking water office, were charged with misconduct, conspiracy, tampering with test results and misdemeanor violations of clean-water law.
The crimes carry maximum penalties of four to five years in prison.
They were accused of failing to order anti-corrosion chemicals added to the water to coat the pipes and prevent them from releasing lead.
Flint utilities administrator Michael Glasgow was also charged Wednesday with tampering with evidence for allegedly falsifying lead water-testing results and with wilful neglect of duty.
Busch is on paid leave. Prysby recently took another job in the agency.
"They failed Michigan families. Indeed, they failed us all," Mr Schuette said. "I don't care where you live."
For months, people in Flint have been relying on filters and bottled water. Some still do not trust what comes out of their taps, even though the city rejoined the Detroit-area water system last autumn and anti-corrosive phosphates are being added to the water.
The governor filled a few jugs of filtered Flint tap water and pledged to drink it for 30 days to show it is safe.
"It's a good first step but it's a small step," Flint resident Melissa Mays said of the criminal charges.
"These are lower-level people, and I want to know who was instructing them to do what they did.
"I think it's important that we can see some form of accountability being laid out, but at the end of the day we still can't drink or bathe in our water safely."
Most US cities stopped installing lead pipes in the 1930s to carry water from main lines under the streets and into homes. But a survey by the American Water Works Association found that 6.5 million of these pipes are still in use.
Some researchers question whether chemical treatment and routine testing for lead in the water are enough, arguing that the only way to remove the threat is to replace the pipes. But the cost could easily be hundreds of millions of dollars or more.