KTVB reports the 10-month-old girl was found unresponsive and not breathing late Friday night in the 500 block of Highland Avenue.
An investigation revealed the child had been left along inside the parked vehicle for several hours during the afternoon and into the evening.
So far, nobody has been charged in connection with the death, but police said they are committed to conducting a thorough investigation.
Police are reminding the public to never leave children or pets unattended in vehicles.
“It simply is not safe to leave an unattended child in a vehicle any time,” Twin Falls Police Chief Craig Kingsbury said. “This becomes especially true during warm temperatures. The interior temperature of a vehicle increases rapidly and this can become deadly for children and even pets. Please do not ever leave children unattended in a car.”