(PITTSBURGH) -- Four people have died in Pennsylvania as severe storms hammered much of the U.S. on Tuesday night -- and the severe weather threat is ongoing on Wednesday.
A long-lived destructive thunderstorm wind event traveled more than 500 miles from eastern Indiana through central Pennsylvania on Tuesday afternoon. Wind gusts reached 80 mph as the more than 60-mile-wide storm complex knocked down trees and power lines along its destructive path.
In Franklin Township in eastern Pennsylvania, high winds knocked down a tree, which then fell onto a car, killing a passenger inside, according to Pennsylvania State Police.
In State College in central Pennsylvania, a 22-year-old man was fatally electrocuted when he was putting out a mulch fire caused by live wires knocked down in the storm, officials said.
Two other victims died in the Pittsburgh area in western Pennsylvania, according to Allegheny County officials.
Over 300,000 customers in Pennsylvania remain without power on Wednesday afternoon.
The four fatalities came as severe weather hammered much of the country from Texas to New York on Tuesday night.
Wind gusts climbed over 100 mph in Texas and neared 90 mph in Missouri. Four confirmed tornadoes struck Oklahoma and Missouri, uprooting large trees, damaging buildings and destroying roofs.
On Wednesday and Thursday, more than 50 million people remain on alert for severe weather from Texas to the Ohio Valley.
Two tornado watches have been issued in Texas, Oklahoma, Arkansas and Louisiana. Damaging wind gusts up to 70 mph and scattered, large hail are also possible.
Anywhere from Abilene, Texas, to Waco, Texas, to Little Rock, Arkansas, may see significant flash flooding on top of the severe storms.
More than 700 flights are canceled in the U.S. on Wednesday, with Dallas' two airports hit the hardest.
Life-threatening flash flooding is also a major threat Wednesday in Texas, Oklahoma, Missouri and Arkansas, with 3 to 6 inches of rain in the forecast.
This comes after 2 to 5 inches of rain fell Tuesday from north Texas to Oklahoma City to Tulsa, Oklahoma. In the last week, this area has seen 800% of its normal rainfall for this time of year -- so adding more rain on top of that will easily spark flash flooding.
Oklahoma City broke its record for wettest April ever on Wednesday -- while this is the city's wettest month overall since May 2015.
The dangerous flash flooding is forecast to be worst in Dallas, southeastern Oklahoma and eastern Arkansas.
The Dallas and Fort Worth, Texas, area is under a flash flood warning.
On Thursday, the severe weather will move east, targeting from Austin, Texas, to Shreveport, Louisiana, to Little Rock to Nashville, Tennessee, to Louisville, Kentucky, to Cleveland. The main threats will be damaging winds and large hail, but brief tornadoes can't be ruled out.