An American family's Disney vacation turned into a nightmare when an alligator snatched their two-year-old boy at the shore of a resort lake and the father was unable to pry the toddler from the animal's jaws, officials said Wednesday.

A search and rescue operation launched after the attack Tuesday night at the Grand Floridian hotel not far from the Magic Kingdom was ongoing, but police said they held out little hope the boy would be found alive.

Walt Disney World said it has shut down all of its Florida resort beaches and marinas out of precaution after the incident.

"We are keeping some hope alive, but it is looking more grave every moment, every hour," Orange County Sheriff's Office spokesman Jeff Williamson told AFP.

READ: Toddler's body found 'completely intact' after gator attack

The mauling was yet more terrible news for a vacation town still reeling from the weekend shooting massacre of 49 people at a gay nightclub in downtown Orlando -- the worst mass shooting in American history. Another 53 were wounded.

"We determined this two-year-old child was playing at the edge of the water, a foot or so into the water, when this alligator came up and attacked the child," Sheriff Jerry Demings told a sunrise news conference.

"The father did his best, tried to rescue the child -- however, to no avail."

The child belonged to a family of five from the Midwestern state of Nebraska that was relaxing on the shore of the man-made Seven Seas Lagoon at the hotel, Demings said.

The alligator emerged and snatched the boy around 9:00 pm Tuesday (0100 GMT Wednesday).

The Grand Floridian is part of the massive Disney resort complex that includes several theme parks, water parks, hotels and golf courses.

"Everyone here at the Walt Disney World Resort is devastated by this tragic accident," Disney communications executive Jacquee Wahler said.

"We are helping the family and doing everything we can to assist law enforcement."


All-out search

Rescuers used sonar and floodlights overnight to pursue their search, as a helicopter hovered overhead. Firefighters stood on the water's edge with infrared cameras scanning the water for the child.

Four gators have been captured and are being analyzed but there was no sign of the child, the Orlando Sentinel reported. A professional gator trapper has been brought in to help, it added.

"We are very hopeful, hoping for the best," Demings said early Wednesday.

"Sometimes you get the worst, but we're certainly hoping for the best."

Alligators are common in Florida, where they can be found in bodies of fresh water across the state, Nick Wiley from the Florida fish and wildlife service told reporters.

However, it is very rare for an alligator to attack a human, Wiley said. There have only been 22 deaths from unprovoked alligator bites documented in Florida since 1948, according to the fish and wildlife service.

There was a no swimming sign at the lake, but no warning about alligators, he added.


'Horrendous' few days for Orlando

Two days before the nightclub massacre, singer Christina Grimmie, a former contestant on the popular TV show "The Voice," was shot and killed by a gunman at Orlando's Plaza Live Theater during a meet and greet event with fans. The gunman later killed himself.

"The past three or four days have been horrendous for our community," Orange County Mayor Teresa Jacobs said Wednesday as she addressed the town's latest crisis, the missing boy.

"I can't comprehend, I can't comprehend what any of this would be like as a parent," said Jacobs, who has a 20-year-old son.