Atlanta — Potent thunderstorms have been blamed for one death and left more than 200,000 people without power across the southern United States. Fierce winds were also expected to wallop parts of several states as new storms form Thursday, forecasters said.

Flash flooding forced overnight rescues outside Philadelphia on Thursday, and 52 million Americans were under the threat of severe weather, as a storm carrying heavy winds, rain and hail moves from the South to the East Coast.

Fallen trees ripped down power lines and crashed into buildings along a line from Texas to Alabama overnight and into Thursday morning, the national Storm Prediction Center reported. A few isolated tornadoes were reported, damaging roofs in the northeast Texas city of Greenville. The weather destroyed buildings and twisted metal throughout the city's downtown area.

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No one was seriously injured. A heat advisory warning has been declared by the National Weather Service over most of Southeast Texas following the storm, with temperatures ranging from 105 to 110 degrees.

In Mississippi, 19-year-old Jackson Salter died when a tree fell on his home Wednesday night, Washington County Coroner Methel Johnson told The Delta Democrat-Times .

More than 70,000 homes and businesses are without power in Arkansas, and more than 30,000 outages each are reported in Texas, Louisiana and Alabama, where crews are out working to remove toppled trees and clear blocked roads. The storms were moving eastward, with more severe weather possible Thursday in Alabama and Georgia all the way up the Eastern Seaboard to Pennsylvania, forecasters said.

The National Weather Service reports "a strong and organized storm system will progress from the Ohio and Tennessee Valleys into the East. Expect severe weather with damaging winds across the Mid-Atlantic and Southeast, while the excessive rain risk moves from the Ohio Valley into the Northeast." A flood watch has been declared over most of Ohio and Pennsylvania.

An area that includes North and South Carolina, eastern Georgia and southern Virginia will see an enhanced risk of wind damage from powerful Thursday afternoon storms, the Storm Prediction Center said. The region is home to 15.6 million people and includes Charlotte, North Carolina.

Downburst winds — strong winds that descend from a thunderstorms and spread out when they hit the ground — appear to be the greatest threat in this area Thursday, said Dan Miller, a meteorologist at the National Weather Service in Columbia, South Carolina.

Such winds hold the potential for serious damage, such as bringing trees and powerlines down and tearing into the shingles and siding on homes, he said.

"It's expected to all come together this afternoon and early evening," Miller said Thursday morning.

Thursday afternoon will also bring the risk of some tornadoes and very large hail to flood-weary residents of the Missouri River Valley in the Midwest, forecasters said.

Chris Smith makes his way through floodwaters to the Macedonia Baptist Church in Westville, New Jersey, Thursday, June 20, 2019. Matt Rourke / AP

In Ohio, heavy rains led to landslides and flooded highways. Flash floods lead to some people to be trapped in their vehicles and several homes were damaged, where some residents were forced to evacuate by boat. The Riverbend Music Center along the Ohio River east of Cincinnati postponed a Thursday evening show that was to feature country star Brantley Gilbert. The venue cited heavy rainfall and the rising river.

Flooding already was causing travel problems, flooding commuter train stations and forcing service to be suspended between Philadelphia and New Jersey. The Delaware River was overflowing its banks in places, and people were being rescued from high water. A supermarket roof collapsed in suburban Philadelphia, causing sprinkler system pipes to break and send water gushing down.

Omar Villafranca contributed to this report.