There are reports of multiple people being swept away by flooding in Virginia as tens of millions of people are at risk of dangerous flash floods in pockets of nearly every region of the contiguous United States Friday,

“If you’ve never seen water rise in front of you in minutes, it’s hard to conceive of how quickly that can happen—and how quickly your life and property can be at risk,” said Rachel Hogan Carr, executive director of the Nurture Nature Center, a nonprofit focused on flood-risk communication.

The National Weather Service released an updated flash flood warning at 6:15 a.m. on Thursday in effect until 9 a.m. The warning is for Clay, Jackson, Carroll, Lafayette and Ray counties.