Ohio's governor is declaring a state of emergency in northwest Ohio, where about 400,000 people are being warned not to drink the water.
Toledo officials issued the warning Saturday after tests revealed the presence of a toxin possibly from algae on Lake Erie.
The warning is affecting several suburbs of Toledo as well as a few areas in southeastern Michigan.
Toledo leaders say they are setting up water distribution centers around Ohio's fourth-largest city. Most stores around Toledo and beyond have run out of bottled water.
Gov. John Kasich's emergency order will allow the state to begin bringing water into the Toledo area.
Toledo's mayor says it's too early to know how long the water advisory will stay in place. More tests are being done and results are expected later Saturday.