A Florida babysitter has been charged with manslaughter after the 10-month-old baby in her care died after being left in a hot car Wednesday, the Baker County Sheriff’s Office said.

Rhonda Jewell, 48, picked up the baby from her mother’s house at 8 a.m. to care for him, and when the mother returned at 1 p.m. they realized the baby had been left inside the vehicle, the sheriff’s office said.

Temperatures in the area were 97 degrees shortly before 1 p.m. Wednesday, according to the National Weather Service.

A sheriff’s incident report says the interior of the vehicle had a recorded temperature of 133 degrees when the child was found. Jacksonville’s NBC affiliate WTLV reported.

It was 97 degrees around 1 pm in the area. On an 80 degree day, the temperature inside a car can rise to 123 degrees in 60 minutes, according the Centers for Disease Control and Prevention.

There were no extreme heat watches or warnings in the Baker County area, which is west of Jacksonville, Thursday night, but the incident occurred as millions of Americans across the South and Southwest remained under a life-threatening heat wave.

More than 119 million people in the US, including in parts of Florida, were under a heat advisory or excessive heat warning Thursday night, according to the National Weather Service.

About 40 children die each year from heat stroke after being trapped in a vehicle, according to the National Highway Traffic Safety Administration.

About 53 percent of those deaths occur when someone forgets a child is in the car, the agency warns. Parents should get in the habit of always checking the back seat before locking the doors, and everyone should always keep cars locked when they’re not being driven, she says.

Jewell was arrested on one count of aggravated homicide of a child, according to the sheriff’s office.

The other children she was caring for were well cared for, according to the sheriff’s office incident report.

Jewell told investigators that after he got home he went inside to interact with the other children and completely forgot the boy was inside the vehicle, the report says.

An attorney listed in online court records as representing Jewell did not immediately respond to a request for comment late Thursday.