To the west, thunderstorms dropped hail as large as tennis balls in Colorado, and dozens of drivers in Nebraska pulled off Interstate 80 with broken windshields.

Forecasters warned of the possibility of powerful thunderstorms during the Tuesday afternoon rush hour in the Kansas City area, as well as more bad weather in Ohio.

A tornado with winds up to 140 mph (225 kph) struck near Trotwood, Ohio, a community of about 24,500 people 8 miles (12 kilometers) outside Dayton. Several apartment buildings were damaged or destroyed, including one complex where the entire roof was torn away, and at least three dozen people were treated for cuts, bumps and bruises.

"If I didn't move quick enough, what could have happened?" said Erica Bohannon of Trotwood, who hid in a closet with her son and their dog. She emerged to find herself looking at the sky. The roof was gone.

Just before midnight, about 40 minutes after that tornado cut through, the National Weather Service tweeted that another one was crossing its path.

Only a few minor injuries were reported in Dayton. Fire Chief Jeffrey Payne called that "pretty miraculous," attributing it to people heeding early warnings. Sirens went off ahead of the storm.

Some of the people treated at the area's Kettering Health Network hospitals were hurt during storm clean-up itself, while others may have waited before seeking treatment from storm injuries, said spokeswoman Elizabeth Long.

A boil-water advisory was issued after the city's pumping stations lost power. Dayton Power & Light said more than 50,000 customers remained without electricity and restoration efforts could take days.

A high school gym in Dayton was designated an emergency shelter until authorities realized it was unusable. Vandalia's school system tweeted that it is ending the year two days early because of building damage. In nearby hard-hit Brookville, where the storm tore off the school's roof, classes were canceled.