(NBC News) - An 18-month-old girl died when her mother "forgot" her in a car for nearly eight hours while at work Tuesday, police said.

Authorities found the girl unresponsive after responding to a "life threatening medical call" at the Panama City elementary school where her mother is a teacher, according to the Bay County Sheriff's Office.

Investigators said the mother, who they identified as Jamie Buckley, left the girl in the vehicle after arriving at the school between 7 and 7:30 a.m. The teacher returned about 3 p.m. to find her daughter still in a car seat.

"Deputies arrived to discover an 18 month old child that was not breathing," the Sheriff's Office statement said in a statement. "EMS arrived and the child ... was pronounced dead at the scene."

The statement added: "The body has been turned over to the Medical Examiner's Office. The investigation continues."