(CNN) — Nearly 4 million homes lost power early Saturday across the Midwest as a fierce line of thunderstorms and winds pounded the region after record-setting temperatures.
The storms moved east from Indiana through Ohio and into West Virginia, according to utility companies. Virginia was hit with power outages to more than 1 million homes.
The outages come as tens of millions in the central and eastern United States are battling a sweltering summer.
Temperatures Friday soared past 100 degrees Fahrenheit from Kansas to Washington, with scorching conditions expected to continue through the weekend and beyond.
“If you don’t have a good pair of boots, it’ll burn clear through to your feet,” said roofer Zach Bruner in Evansville, Indiana, where he said the 103-degree temperatures were spiking to 130 on the job site.
The severe thunderstorms moving across the Midwest are fueled by the high temperatures, bringing with them lightning and wind gusts as strong as 80 mph, according to the National Weather Service.
The massive systems left one in three Americans baking in scorching heat, has threatened lives and caused misery for those not fortunate enough to find a splash of cool water or air conditioning.
By Friday afternoon, temperatures had climbed to 100 degrees in Indianapolis; 101 in Richmond, Virginia; and 102 degrees in St. Louis, where highs were forecast to stay above 100 through Thursday, the National Weather Service said.
And it felt even hotter in some places, with the heat index topping out around 115 degrees.
The Jackson County medical examiner in western Missouri is investigating three deaths that may be related to the heat, according to the Kansas City Health Department.
The National Weather Service issued an excessive heat warning through Sunday for eastern Missouri, including St. Louis, where temperatures are expected to soar up to 106 this weekend.
“Heat-related illness such as heat exhaustion or heat stroke are a real threat,” the weather agency said. “This is especially true because of the longevity of this heat wave and the effects of extreme heat are cumulative.”
In Memphis, where highs hit 105 degrees Friday, firefighters went door to door, checking on residents. Churches and faith-based institutions were also urged to ask people to check on their neighbors and relatives.
“Please, if you know of someone who doesn’t have air conditioning or who might be struggling with the heat, just stop by and see how they are doing,” Mayor A.C. Wharton Jr. said.
The weather service posted excessive heat warnings for 12 states, from Nebraska to New Jersey, with watches and advisories posted for at least six other states. Arizona was also under an excessive heat warning.
Baltimore Mayor Stephanie Rawlings-Blake activated the city’s emergency operations to coordinate storm recovery operations. In West Virginia, Gov. Earl Ray Tomblin declared a state of emergency for the entire state after the powerful storms.