A monster storm peppered a 1,500-mile arc with 10 reported tornadoes, grapefruit-sized hail and winds of up to 80 mph Wednesday — and forecasters warned millions of Americans to brace for a second round Thursday.
Hail of up to 4 inches in diameter smashed buildings and cars and high winds tore off roofs and downed trees, as wild weather hit 12 states.
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Elsewhere, a student at the University of Dayton in Ohio was seriously injured after he was struck by lightning. And four elementary students in Tulsa, Oklahoma, were hospitalized after their school bus rolled off Highway 75 in bad weather, the Tulsa World newspaper reported.
Despite the widespread damage, the first day of the predicted two-day event was not quite as severe as the onslaught feared by weather professionals.
"We were expecting a lot more," Weather Channel lead meteorologist Kevin Roth said. "Despite the damage, mainly caused by the wind and hail, you could say it didn't not quite live up to expectations, which is a good thing when it comes to severe weather."
Most of the first round of weather was done by midnight ET. Models were still shifting, but Roth said there could be a one-two punch effect on Thursday with two batches of severe weather hitting in the morning and then the afternoon.
Many of the same areas hit on Wednesday would likely be hit again, Roth said, with the worst of the storm possibly shifting east and north slightly toward the Ohio Valley and further into the Great Lakes.
NBC News' Shamar Walters contributed to this report.