Seven families in Flint, Michigan, filed a class-action lawsuit on Monday, seeking to hold a raft of city and state officials responsible for the lead-poisoning crisis that has made Flint into a symbol of government failure and environmental disaster, NBC News reported. 

The suit is the latest in a tide of litigation spawned by the crisis. Lawyers will ask the courts to certify a class action that would cover any Flint kids who were poisoned when water from the Flint River corroded aging pipes and leached lead into the system.

Flint mom Melissa Lightfoot said that before the city changed water sources, her children were tested for lead and were not found to be in danger. But by late 2014, their levels were above 5 micrograms per deciliter, which shows an alarming level of exposure.

Doctors initially assumed it was from paint, but Lightfoot lives in Section 8 housing that was certified lead-free, she said. After several retests, she said, her pediatrician told her, “It could be the water.”