Police in southwestern Idaho say they are investigating the death of a baby girl who was left in a car as temperatures in the region neared 100 degrees.

A family in the small town of New Plymouth, about 50 miles northwest of the state capital Boise, called police around 5 p.m. Saturday to report that their child had been left in the car and wasn't breathing, the Payette County Sheriff's Office said in a news release.

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The child, under 1 year old, was transported to a hospital where she was pronounced dead. The cause of death hasn’t been confirmed, according to the sheriff's office, which is investigating the death along with Idaho State Police.

Payette County Sheriff Andrew Creech told the Idaho Statesman that law enforcement has not yet determined how long the girl was left in the car.

Temperatures in southwestern Idaho neared 100 degrees on Saturday, according to the National Weather Service.