The attack happened in a restricted area of Silver Springs Nature Park.
"A wild alligator came out from underneath one of the older service vessels," said Eric Hutchinson, Butte's co-worker.
"Pete did not absolutely see it," Hutchinson said. "It grabbed him by the neck and shoulder. Pete is a very large man. He obviously fought his way out of it and survived.''
The gator was later captured and put down.
The injured diver remains in serious condition.