ALPINE (CBS 8/ CNS) - A toddler was found dead under suspicious circumstances in eastern San Diego County Tuesday, authorities reported.

Deputies and medics responding to a report that a child had stopped breathing in a motor home parked on a property in the 300 block of Hunter Lane in Alpine found the lifeless 18-month-old girl shortly after noon, according to sheriff's officials.

According to investigators, the 21-year-old mother found her baby daughter in the motor-home around noon. The mother's Facebook page was filled with posts of support. 

Following unsuccessful attempts to revive the toddler, she was pronounced dead at the scene. Her name was withheld pending full family notification.

"Based on the circumstances and the presence of ... injuries to the victim, sheriff's homicide and child-abuse detectives were called to the scene and have assumed investigative responsibility," Lt. Kenneth Nelson said.

The Medical Examiner's Office will determine the cause of the child's death.

CBS News 8 has learned the identity of the infant and the mother, but will not make the information public until the medical examiner publicly releases the information.