CHARLESTON, S.C. (AP) — A toddler died inside a hot car on Friday after her mother forgot that she left the girl in the vehicle parked outside a South Carolina high school, according to a county coroner.

Berkeley County Coroner Darnell Hartwell told The Post and Courier that he believes the 16-month-old girl died due to heat, although an autopsy will be performed. The temperature inside the car likely exceeded 100 degrees F (about 38 degrees C), the coroner said.

The child’s mother works at Bishop England High School, in Charleston, and had parked her sport utility vehicle in front of the private school on Friday morning. A passerby found the child in a car seat roughly six hours later and called 911, according to the coroner.

Hartwell said the child could have survived only minutes inside the car.

“I definitely feel confident that it was triple digits within that car at peak time of today,” he said.

Bishop England canceled its Friday night football game and classes on Monday.

“We ask that you please keep this family and our school community in your prayers during this unspeakably difficult time,” Bishop England High School President Patrick Finneran wrote in an email to families.

Hartwell said police investigators will conduct interviews and present their findings to a county solicitor’s office.