The distraught father of a two-year-old boy dragged off and killed by an alligator at the Walt Disney World Resort in Florida last month has said he was attacked by a second alligator as he fought to save his son.

A sheriff said charges are unlikely against a Nebraska couple after an alligator killed their two-year-old son by snatching him out of shallow water at a Walt Disney World beach, but the entertainment giant is reviewing whether to add alligator warning signs.

Wildlife officials have pulled four alligators from a lagoon at Walt Disney World after a two-year-old boy was dragged into the water by an alligator.

A search is under way for a two-year-old boy who was dragged into the water by an alligator near Disney's Grand Floridian Resort and Spa, authorities said.