Violent storms that hit the D.C. area late Friday were blamed for the deaths of two people while it emerged that five people, including three young children, may have died due to the severe heat affecting much of the country.
The storms wiped out power to more than 2 million people across the eastern United States. Widespread power outages were reported from Indiana to New Jersey, with the bulk of the service interruptions concentrated on Washington, D.C., and the surrounding areas.
Fallen trees were blamed for two deaths in Springfield, Va. — a 90-year-old woman in her home and a man driving a car, Fairfax County police spokeswoman Mary Ann Jennings said early Saturday.
In addition, a park police officer was injured by an uprooted tree in the northern Virginia county, and an 18-year-old man was struck by a power line, Jennings said. He was in stable condition after receiving CPR, Jennings said.
Earlier Friday, the nation's capital reached 104 degrees — topping a record of 101 set in 1934.
The boys, aged 3 and 5, had been playing outside Thursday. The younger boy died Thursday, and the older boy on Friday afternoon, according to Eric Blach, administrator for the Bradley County Medical Examiner's Office.
Video: How hot will it get this weekend? (on this page)In Kansas City, Missouri, city health officials said Friday they were investigating the deaths of three area residents, including a baby boy, to determine if they were heat-related, according to Reuters.
Early Saturday, the National Weather Service issued excessive heat warnings for parts of Maryland, Delaware, Pennsylvania, D.C., Virginia, North and South Carolina, Georgia, Indiana, Ohio, Illinois, Missouri, Kansas, Kentucky, Alabama, Tennessee and Arizona.
Weather.com published a map of the U.S. showing areas at risk of severe thunderstorms Saturday, with an area from Iowa to the Mid-Atlantic at risk.
"Another round of widespread damaging winds may materialize in these hard-hit areas," it warned. "A second area of severe weather is possible for the central and northern Plains, but those storms may be more isolated in nature."
Story: Heat hub for US is Kansas farm town -- not Death Valley
It said severe thunderstorm would typically form at the northern edge of areas of excessive heat.
"A powerful derecho developed Friday over Indiana and marched eastward across Ohio, the Virginias and into Maryland and Delaware, causing widespread wind damage with gusts over 90 miles per hour in some cases," it added.
Slideshow: Summertime living (on this page)West Virginia Gov. Earl Ray Tomblin declared a state of emergency after more than 500,000 customers in 27 counties were left without electricity because of the storm.
More than 20 elderly residents at an apartment home in Indianapolis were displaced when the facility lost power due to a downed tree.
Most were bused to a Red Cross facility to spend the night, and others who depend on oxygen assistance were given other accommodations, the fire department said.
The storms, sometimes packing 70 mph winds, toppled three tractor trailers on Interstate 75 near Findlay, Ohio.
At least four utility poles fell on a road in Columbus, Ohio, making it too dangerous for people in four cars to get out, police said. One person was taken to a hospital.
Pepco reported hundreds of thousands of outages in the District of Columbia and Montgomery and Prince George's counties, Md.
"We have more than half our system down," said Pepco spokeswoman Myra Oppel. "This is definitely going to be a multi-day outage."
In the Washington, D.C., area, the Metrorail subway trains were returned to their endpoints due to the storms and related damage, officials said.
"It has had a widespread effect on the region," Metro spokesman Dan Stessel said early Saturday.
He said about 17 train stations were operating on backup power due to local power outages, but that he didn't anticipate service being disrupted on Saturday.
The Associated Press contributed to this report.