Young Tristan came to the rescue of his 2-year-old sister when he found her floating, unconscious in the family's pool.
While his mother and grandmother frantically called for help, Tristin sprung into action.
"I went running outside and I did CPR on her," he explained.
Tristin said he learned how to perform CPR from television.
Doctors say the young hero saved his sister's life. She is expected to be just fine.