The accident in the 7900 block of Knollwood Road was reported shortly before 2 p.m., according to the San Diego Fire-Rescue Department.
Medics arrived to find the 2-year-old boy's mother trying to revive him with mouth-to-mouth resuscitation, SDFRD Capt. Joe Amador said. Emergency personnel took over the lifesaving efforts, then took the child to Paradise Valley Hospital in National City. He is in critical condition.
Details about the incident were not immediately available, though preliminary reports indicated that the toddler had been found unconscious in a backyard pool.