Dozens of false killer whales, a type of dolphin, are dead following a stranding in Everglades National Park in South Florida, officials said Monday.

A total of 95 dolphins became stranded off Hog Key, according to officials with National Oceanic and Atmospheric Administration Fisheries. Some of the dolphins were deeply embedded into mangroves.

One whale has been seen alive and another 13 or 14 are unaccounted for, officials said. The stranding was discovered Saturday afternoon. Seventy-two dolphins died and nine were humanely euthanized.

A viewer named John Goldstein recorded video of the false killer whales swimming in Everglades National Park over the weekend.

"There was unfortunately not much that we could do for them. They were high and dry on very wide mud flats and trapped in mangroves. So it was a very unfortunate situation," NOAA Fisheries' Dr. Erin Fougeres said. "It's in a very very challenging location. It's very remote in the far western Everglades. About an hour to an hour and a half by boat to get there."

95 false killer whales stranded off Hog Key, 81 dead, 1 seen alive, ~13 unaccounted for pic.twitter.com/rrltA7iVB6 — NOAA Fish Southeast (@NOAAFish_SERO) January 16, 2017

The area around the scene has been closed by the National Park Service, with no flyovers or boats allowed in the area for safety.

The cause of the stranding is yet to be determined. Necropsies are already being performed and the team continues to take samples.

NOAA Fisheries says the false killer whales can grow up to 20-foot long and weigh about 1,500 pounds, and are known to strand in large groups.

There have only been two previous strandings of False Killer Whales in Florida. One in 1986 in Key West where 28 animals were involved and another in 1989 at Cedar Key, which is near Tampa. That incident had 40 dolphins and most of them were able to swim just three were beached.

NOAA Fisheries is still investigating the recent stranding.

"It's the largest mass stranding we've had in of this species in the U.S." Dr. Fougeres said.

Officials are asking anyone who comes across any live or stranded animals to report it to the stranding network.