Officials are reporting at least three deaths amid a storm system that downed trees and power lines and left about half a million customers in the dark across Pennsylvania, Ohio and neighboring states.

At least four people were killed in Pennsylvania on Tuesday and hundreds of thousands of customers were without power after severe weather that had torn across the High Plains and Upper Midwest earlier this week pushed into the Northeast and Canada.

Record rainfall and severe thunderstorms will mean a heightened risk of flash flooding across the south-central United States through early Thursday.