PALM BAY, Fla. -

Palm Bay police are investigating the drowning of a 15-month-old boy on Wednesday afternoon.

Police said they received reports of an infant found in a backyard swimming pool in the 200 block of Nemo Circle at around 3 p.m.

When rescuers arrived, the boy was unresponsive, according to police. Police said the boy, identified as Jacob Whitley, was being airlifted to the hospital when he was pronounced dead.

Police said the mother of the boy was home alone with her two children, a 3-year-old boy and the victim. The great-grandparents returned home and found the mother in a back room of the home and the 3-year-old wandering about.

Police said the grandparents began searching for the boy when the mother found the boy in the pool, not breathing, and jumped in to get him.

Detectives are investigating what caused the boy to fall into the pool.

Watch Local 6 for more on this story.