Butler County Sheriff Kelly Herzet called the death “a tragedy.”
"She had commented that she had been very tired. She'd been up some of the night before off and on. Don't know if it was with children or for what reason, but she felt like she needed a nap. She laid down about 12:30 p.m. and slept till about 4 o'clock," Herzet said, according to KAKE.
The family had six children, five of them adopted, between the ages of 3 months and 13 years old.
"It seems like a very good family, very well-natured, took very good care of their children. Like I said, it's been a very tragic event that's occurred there," the sheriff said.
The group KidsandCars.org said on its website that 52 children died in hot cars in 2018, and 11 have died so far this year.