Witnesses said Michael Robert Keller ran down the hill and dug the girl out with his bare hands. She was hospitalized with minor injuries.
A section of the beach was closed as investigators looked into what caused the slide. Authorities also forced two dozen RVs to move because they were too close to the unstable hillside.
Angelina Ciucci of the North County Fire Authority said erosion is an ongoing problem at hillsides along the coast.