Beach Safety Capt. Tammy Marris said officials were investigating how the South Carolina woman and her three children ended up in the water Tuesday, the Daytona News-Journal reported.
Marris said the woman was driving on the sand but it wasn't clear how her vehicle wound up in the surf.
The car was submerged when the family members were rescued, the News-Journal said.
Marris said the family was taken to a medical center as a precaution and the minivan was towed from the ocean.