A number of recent deaths of infants and toddlers inside hot vehicles have triggered safety warnings from safety groups and the U.S. government.
Since June 13, eight children have died of hyperthermia and the death toll since the start of the year is 18, researcher Jan Null, an adjunct professor of meteorology at San Francisco State University, told the Associated Press.
A number of the recent deaths involved children who went inside an unlocked vehicle on a hot day and couldn't get out of the car.
Parents should never leave children in an unattended vehicle or allow children to play in cars and trucks, say government and safety experts.
"These really are good parents who love these kids who make a mistake that turns out to be fatal," David Strickland, administrator of the National Highway Traffic Safety Administration, told the AP.