Crews arrived on scene within three minutes, where family members were performing CPR the child, who was transported to a nearby hospital, where he later died.
"There was no fence around the pool, no barriers," El Mirage Fire Chief Howard Munding told KTAR.
He went on to admonish parents of young children to be vigilant around pools as summer approaches.
"Even if you do have a fence, you've got to watch them like a hawk," he said.
Details of how long the child had been in the pool are unknown.