It's happening in Socastee, west of Myrtle Beach.
WPDE-TV reports Horry County Police, Horry County Fire Rescue, and South Carolina Department of Natural Resources crews are involved in the search.
Lt. Denis says they have a woman in custody who told them she threw the baby in the water. Crews are still searching pic.twitter.com/fGA24y6TTQ— Erin MacPherson (@ErinWPDE) November 3, 2015
Investigators have not released the child's name or identified her mother, but they did release a picture of the child.