(CNN) — Twin 3-year-old girls in foster care were found dead Sunday in a hot vehicle in Georgia, according to a statement by the city of Hinesville.

Preliminary autopsy results released by the Liberty County Coroner’s Office on Tuesday said the cause of death was heatstroke.

The temperature was around 92 degrees at the time, according to CNN weather.

An investigation is underway.



The twin girls’ biological mother shared photos of Raelynn and Payton Keyes with a reporter.

She said she and her husband would see the twins every Friday after they were taken from them and put in foster care more than a year ago.

Skye Keyes said if anyone had a chance to be around the twins they knew they were a burst of life and would a smile on anyone’s face.

She said they were born premature, but grew to be healthy, energetic little girls.

They were also a few weeks shy of turning four years old.

“They’re little prissy tomboys put it that way. They tagged around with their brother but they are as girly as you can get at the same time but happy go lucky kids and attached to mom and dad but they just … they were just perfect,” Keyes said.

Arrangements have not been made for their burial.

According to KidsAndCars.org, over 900 children have died in hot cars nationwide since 1990.

BY THE NUMBERS

Year — Total

2019 — 48

2018 — 54*

2017 — 43

2016 — 39

The average number of deaths per year: 38 (one every 9 days), according to KidsandCars.org.

*Year with the most fatalities: 2018 (54 deaths)

Source: KidsandCars.org.