More than 250,000 homes and businesses in the eastern United States were without power Tuesday after powerful thunderstorms battered the region, killing at least two people and cancelling thousands of flights.

In South Carolina, where more than 11,000 customers remained without power Tuesday afternoon, a 15-year-old boy was killed after a tree fell on him as he got out of a car, according to the Anderson County Office of the Coroner. In Florence, Alabama, police said a 28-year-old man died after he was struck by lightning, WAAY-TV reported.

More than 1,700 U.S. flights were canceled and nearly 9,000 were delayed Monday, according to flight tracking website FlightAware. More than 2,000 U.S. flights were canceled or delayed Tuesday as the storm system brought heavy rainfall to New England.

Severe thunderstorms and winds in excess of 60 mph caused damage Monday in southern Pennsylvania, central Maryland and northern Virginia, Andrew Orrison, a meteorologist with the National Weather Service in College Park, Maryland, told USA TODAY. The storms toppled trees, sent power lines crashing into roads and some homes and ripped roofs from buildings, according to preliminary reports from the National Weather Service.

“We saw the clouds coming and could hear a rumbling in the distance,” Don Tomovich, whose home was damaged, told 6ABC-TV in Philadelphia. “We went into the house and we were on the first floor, and before we could blink an eye the winds just came right through the back of our house.”

Storms bring damaging winds, hail and flash flooding

Orrison said there were numerous reports of golf ball-sized hail across the mid-Atlantic and flash flooding in the Baltimore metropolitan area as the storms swept through. The Knoxville Utilities Board said on X, formerly Twitter, the damage across its service area in Tennessee was “widespread and extensive” and will likely take several days to repair.

In Westminster, Maryland dozens of people including 14 children were rescued after 34 cars were trapped on Route 140 by downed power lines, according to Maryland State Police. The motorists were trapped for more than 5 hours, according to local media. Police said on X Tuesday they are still working to return car keys to the owners of the stranded vehicles.

More than 29.5 million people were under tornado watches Monday afternoon, according to the weather service, and more than 1.1 million customers lost power as the storms struck. At least one tornado was confirmed Monday evening in McGraw, about 30 miles south of Syracuse, New York, the New York Times reported. Orrison said he is not aware of any confirmed reports of tornadoes, but that could change as local weather services crews conduct surveys to determine if damage was caused by tornadoes.

Bob Van Dillen, a Fox Weather meteorologist, told USA TODAY he's seen more than 530 reports of wind damage in Mississippi, Alabama, Georgia, the Carolinas and "all the way up the eastern seaboard" to northern Virginia. He said tornado damage may be seen in upstate New York, northern Virginia, eastern Kentucky, central West Virginia and possibly North Carolina.

"This storm was unusual because it was so powerful," Van Dillen said. "It's something you would see really in springtime."

Severe weather could continue this week

Orrison said the storm system that brought severe weather to the mid-Atlantic and Southeast Monday is bringing heavy rainfall to parts of New England.

"There will be concerns for flash flooding there today where locally a few inches of rain may occur," Orrison said.

He said there is the possibility of large hail and strong gusty winds across the Gulf Coast states and parts of the Southeast, including areas of Mississippi, Alabama and southern Georgia Tuesday evening. He said severe weather could also hit portions of the central High Plains region, including areas of eastern Colorado, Nebraska and parts of Kansas Tuesday afternoon and overnight.

The turbulent weather could plague much of the East for the rest of the week, forecasters said.

"The pattern this week will feature frequent showers and thunderstorms, typically every other day or so, across much of the East," AccuWeather Senior Meteorologist Alex Sosnowski said. "Even though it may not rain as much or as often as it did in July, conditions may again pose daily challenges for outdoor plans and travel."

Heat still plagues the South

Though forecasters said the storms will likely keep intense heat at bay in the Northeast and mid-Atlantic, "dangerously hot daytime temperatures" were expected across the South Tuesday, according to the National Weather Service. The record highs would persist from the Desert Southwest into Texas and extend eastward along the Gulf Coast into parts of the Southeast and Florida, the weather service said.

Highs could hit the upper 90s to the lower 100s with a heat index − what the temperature feels like when relative humidity is combined with the air temperature − of 105 to 115 degrees in those areas, according to the weather service. The hot temperatures, dry ground conditions, low humidity, and gusty winds would elevate the wildfire risk in the Four Corners states into Texas, the weather service said.

"We'll have more severe weather for the South today," Van Dillen said. "And of course, it's still smoking hot across the Gulf Coast."

Contributing: The Associated Press