John Michael Ortiz of Sinton and his family were picnicking Sunday at J.P. Luby Beach on Padre Island, the Corpus Christi Caller-Times reported.
Dolores Ortiz, the boy's aunt and adoptive mother, said his 9-year-old brother was so upset when he returned to the family that at first he could not speak. He eventually said a wave had knocked the two boys down and pulled John Michael away.
A man walking on the beach found John Michael unconscious. The boy was pronounced dead at a hospital in Corpus Christi.
Police said the death is being treated as an accident.