A four-month-old girl died after her grandmother forgot the baby was in her car and left her there for hours while she was working, authorities say.

Investigators were called around 5.30pm Friday to the parking lot of the Apple Creek Learning Center daycare in Luther, Oklahoma, where they found the child dead in the car's back seat.

Oklahoma County Sheriff's Office spokesman Mark Opgrande said the grandmother has full custody of the infant and intended to drop her off at the daycare on her way to work in Oklahoma City, where the outside temperature reached 31C.

"The intention was to drop the child off here at the learning center but that didn't happen, and so the only thing we can surmise is that the child was in - apparently - the back of the vehicle at the grandmother's place of work for the entire day," Opgrande told KFOR.


At the end of the day she arrived at the daycare to pick up the child the Daily Mail reported.

"They informed her that she did not drop off the child and they went, proceeded to look for the child inside the daycare," Opgrande said.

"They couldn't find her. That's when they went out to the vehicle, and then discovered her outside in the back of the car. She was deceased."

The grandmother was questioned by police and has since been released.

"She's obviously distraught," he said. "This is a tragic situation and that's why we remind parents all the time. It's hot out and things like this aren't supposed to happen, but they do."

Oklahoma County Sheriff's Office is investigating the child's death at the request of Luther Police.

Opgrande said a report will be forwarded to prosecutors to consider charges.

The names of the infant and the grandmother have not yet been released by police.