OKLAHOMA CITY — At least two people drowned when their vehicles were caught in floodwaters in Oklahoma on Wednesday as slow-moving thunderstorms inundated roads across parts of that state and Texas, authorities said, while Pennsylvania residents picked up from a powerful storm that left three people dead.

Heavy rains and severe thunderstorms will mean a heightened risk of flash flooding across the south-central U.S. through early today, the National Weather Service said.

The storms drenched much of southern Oklahoma and northern Texas, flooding and washing out roads and causing hundreds of flights to be canceled or delayed at major airports.

One man drowned in Oklahoma after his vehicle got swept off a Pottawatomie County highway, said Sheriff Freeland Wood. A deputy couldn’t save him.

In Pennsylvania, storms knocked out power to hundreds of thousands. Three people were killed, two by electrocution and a third by a falling tree.

Some neighboring states also had outages.

— The Associated Press