Fresno police collected evidence at the home where an 18 month old boy was found unconscious around 7:45 Monday night.
Mike Doyle, Fresno Police Department, says "The child's mother was at home and so was the grandfather. For unknown reasons, we're still investigating how it happened. Other circumstances on why it's just an unfortunate accident."
Investigators say the family did not have a fence around their pool. It appears the child was in the water for several minutes before he was discovered.
Police say family members were distraught and rode in the ambulance as the boy was rushed to the hospital. He was pronounced dead shortly after he arrived.
"It's a horrible tragedy and that's what they're finding out too," says Doyle.
An autopsy is expected within the next few days. Police say at this point the toddler's death appears to be accidental.
