OKLAHOMA CITY (AP) A 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 Thursday, the National Weather Service said.

Rains drench parts of Oklahoma and Texas

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.

“My deputy went in to try and save him, and he got caught up in the same mess,” Wood said.

The deputy was treated at a local hospital and released, Wood said. Floodwaters closed nearly three dozen roadways in the county.

Another drowning was reported in neighboring Lincoln County after a driver’s vehicle got trapped in floodwaters along a highway northwest of Prague, Oklahoma Highway Patrol spokesperson Sarah Stewart said.

Authorities in the state reported that numerous drivers were rescued from floodwaters, while some residents in the small city of Lexington were evacuated from homes as the waters rose.

Oklahoma City set a record Wednesday with 11.94 inches (30.33 centimeters) of rain in April, surpassing the 1947 mark of 11.91 inches, according to Oklahoma State Climatologist Gary McManus.

Oklahoma was poised to break the 1942 record for statewide rainfall average of 8.32 inches (21.13 centimeters) for the month, McManus said.

By Wednesday night parts of more than a dozen highways were closed due to flooding and three shelters opened in Comanche County.

In the Dallas area, departures were grounded at Dallas Love Field and Dallas-Fort Worth International Airport for part of the day because of thunderstorms, according to the Federal Aviation Administration. Hundreds of flights were canceled at DFW International Airport and dozens more at Love Field, according to FlightAware.

Pennsylvania storm knocks out power to hundreds of thousands

Tuesday night’s powerful storm knocked out power to more than 425,000 customers in Pennsylvania and 40,000 in Ohio, according to PowerOutage.us. Neighboring states also reported thousands of outages. About 300,000 Pennsylvania customers and nearly 19,000 in Ohio were without power late Wednesday.

A spokesperson for Pittsburgh-based Duquesne Light called the storm’s damage “unprecedented” for knocking out electricity, toppling trees and snapping power poles.

About 325,000 customers lost power and more than 150,000 were still in the dark in the evening, the company said on its website. The utility was bringing in about 400 people from neighboring utility contractors to help restore electricity.

Pennsylvania Gov. Josh Shapiro surveyed damage in Allegheny County on Wednesday and stopped by Fiori’s, a popular pizzeria that had had its roof ripped off by the storm.

Authorities say 3 deaths are related to storm in Pennsylvania

A Pennsylvania man was electrocuted on Tuesday evening while trying to extinguish a mulch fire near a utility pole as severe weather hit the State College area, police said. The 22-year-old man died at the scene. State College police said they believe the man’s death to be storm-related.

In Pittsburgh, first responders were called to the South Side Slopes area for reports of a person electrocuted by live wires, and that person died on the scene, according to the Pittsburgh Public Safety Department. The department urged residents to use extreme caution when moving through the city, citing multiple hazards such as downed trees and possible live wires.

Allegheny County officials confirmed that a 67-year-old man was killed by a fallen tree at a home in Ross Township, just outside Pittsburgh.

Teams investigating wind damage in Pittsburgh area

The National Weather Service’s Pittsburgh office said destructive wind damage was seen across its region. Straight-line winds gusted over 80 mph to 90 mph (129 kph to 145 kph), which is stronger than many EF0 and EF1 tornadoes typically seen in the area, the weather service office said in a social media post.

The line of thunderstorms that swept across Pennsylvania on Tuesday night formed what’s called a “bow echo,” or a bow-shaped line of incredibly strong winds that are strongest at the apex of the curve, according to weather service meteorologist John Bowen in State College. Damage was most severe where the apex passed, he said.

Pittsburgh International Airport recorded its third-highest wind gust in modern history at 71 mph (114 kph), according to Liana Lupo, a meteorologist with the weather service’s Pittsburgh office. A team investigated wind damage in Wilkinsburg, just outside Pittsburgh, but could not conclusively say a tornado had touched down, Lupo said.

Levy reported from Harrisburg, Pennsylvania. Associated Press writers Jamie Stengle in Dallas and Sarah Brumfield in Cockeysville, Maryland, contributed.