A 5-year-old died at his home near Houston on Monday after being left in a hot car for hours, according to Harris County Sheriff Ed Gonzalez.

Gonzalez tweeted at 3:19 p.m. on June 21 that officers had arrived at the home and begun their investigation. The boy was pronounced dead at the scene.

Gonzalez shared with ABC 13 in Houston that the boy’s mother and her two children — the 5-year-old victim and his 8-year-old sister — went to the store to buy party decorations for the 8-year-old’s birthday party earlier in the day.

In their rush, Gonzalez said, the mother and 8-year-old forgot to unbuckle the younger child from his car seat and went inside to begin setting up for the party. The boy’s mother reportedly did not realize he was missing until calling for him two to three hours later.

Investigators determined that the boy knew how to unbuckle himself from his car seat and exit his own car, so they say the mother may have assumed he got himself out of the vehicle, Gonzalez said. But the car the family drove that day was a rental, so the boy may not have been familiar with the door controls, he explained, which may have factored into the accident.

“Perhaps the child wasn’t as familiar with” the rental car, the sheriff said. “The door didn’t have any kind of child safety lock.” It is unclear, at this time, whether the mother will face charges in this incident.

The temperature at Houston Intercontinental Airport on Monday was 102, breaking a record that stood since 1902, according to the National Weather Service in Houston.

The National Safety Council has compiled reports of hot car deaths since 1998 and says temperatures can rise 40 degrees inside a car within a half-hour when left in the sun.

The data shows this is the fifth hot-car death of 2022 and number 912 nationally since the council started collecting data in 1998. Of those, 136 occurred in Texas, accounting for almost 15% of the national total.

The NSC says approximately 38 children under 15 die from heatstroke yearly after being left in hot cars. Those deaths peak in hot summer months but can happen at any time.