Sheriff's deputies said they were dispatched Monday at 2:30 p.m. to West Pine Street in Daisetta after family members reported their 1-year-old was missing.
As deputies were responding to the scene, a family member found the girl in an above-ground swimming pool. The child was given CPR, but she did not respond, according to a lead investigator.
According to a release, the parents of the 1-year-old told deputies they had put her down for a nap. When they checked on her two hours later, she was not in bed.
Deputies say it appears the girl got up from her nap and wandered into the pool.
An investigation in the case is ongoing and an autopsy will determine exactly how she died.