A dad watched in horror as a reptile clenched its jaws around his two-year-old son while relaxing near the five-star Grand Floridian Resort & Spa in Orlando, US.
The reptile then pulled the toddler into the Seven Seas Lagoon.
A search is now underway to try and find the boy.
The Florida Fish and Wildlife Conservation Commission said it had now "euthanized" four alligators.
However, it found no evidence that those animals were involved in the disappearance of the boy.
Search and rescue teams have been searching the water for the tot since he was attacked by the gator in Florida shortly before 9.30pm yesterday local time (2.30am today UK time).
More than 50 people, including wildlife officials, have been involved in the search effort, while a diving team is on standby, Orange County Sheriff Jerry Demings said.