This article originally appeared on Huffington Post by Hilary Hanson on July 23rd, 2016.

A 4-year-old girl in Williamsport, Pennsylvania has died after spending hours in the back seat of a hot car, local media report.

A woman who cares for the girl usually takes her to daycare in the morning, but on Friday she drove to work without dropping the child off, reported local news station WNEP. The girl remained in the back seat until 3:30 p.m. on a day when temperatures outside reached 97 degrees.

By the time the woman came back to the vehicle, the girl was unconscious. She later died in the hospital.

The relationship between the woman and the girl is unclear. The Williamsport police could not be reached for comment.

An excessive heat warning is in effect over the weekend for much of the country, including parts of Pennsylvania.

Temperatures inside cars can skyrocket faster than many people realize. This chart from the American Veterinary Medical Association (since hot cars are also a major hazard to pets) shows that even when the outside air temperature is only 70 degrees Fahrenheit, the temperature inside a car can reach nearly 90 degrees within 10 minutes, and nearly 100 degrees within 20 minutes.

And hot temperatures are riskier for kids than adults, since a child’s smaller body can heat up three to five times faster than an adult’s, Kate Carr, CEO of the nonprofit Safe Kids Worldwide, told Once a child’s body temperature reaches 104 degrees, major organs can begin to shut down.

“Deaths from heatstroke in cars have occurred 11 months of the year in nearly every state in the country,” Carr told the outlet.