The US National Weather Service has sounded a high-temperature alert in 30 states, after a heat wave resulted in the death of at least 24 people.
The weather service also said staying outdoors for any length of time was dangerous, especially for seniors, children, heart patients and people with breathing problems, EFE news agency reported.
Friday was an extremely hot day in several states on the east coast, according to officials.
In New Jersey, authorities said some 100 people, mostly teenagers, fainted from the heat in Camden, where over 12,000 people had gathered for a rock concert.
The first death related to the heat wave occurred in Kansas City.
Authorities reported 13 heat-related deaths in Missouri, including two women over 70.
Citing the Chicago Sun-times, Xinhua reported that autopsies on Friday revealed that at least seven people from the Chicago area died from heat related causes in the last three scorching days.
Officials said an 18-year-old man collapsed after biking, running and being outdoors with family and friends. Six other elder Chicagoans also died from heat related causes.