Four of the whales had to be euthanized Wednesday, and six others already had died, said Blair Mase, the marine mammal stranding network coordinator for the National Oceanic and Atmospheric Administration. At least three could be seen on the beach, out of the water.
Park spokeswoman Linda Friar said rescuers were trying to surround the whales with boats about 75 feet from shore and nudge them out of the roughly 3-foot-deep salt water back to sea.
"They are trying to herd the animals out to sea," Friar said. "They are not cooperating."
Workers tried to nudge the whales out to sea a day earlier with no success. The whales are stranded in a remote area that takes more than an hour to reach by boat from the nearest boat ramp.
"This scenario is very challenging because of where they are," Mase said. Officials typically have access to heavy equipment to rescue stranded whales, but that isn't an option where the whales are now.
Furthermore, the area is so shallow that it's difficult to get the mammals enough water to propel them back to sea. A team of biologists was still assessing the whales Wednesday.
Officials don't know how long the whales been stranded or how they got there. The whales usually swim together in large groups and tend to follow a dominant male leader, so it's not uncommon for multiple whales to get stranded at once.
At least one other group of whales has stranded in the park in the past 10 years.
"It's not uncommon," Friar said. "But it's not something that happens a lot."
Mase said the whales are known to inhabit deep water, "so they are very out of their home range."
Associated Press writer Christine Armario contributed to this report from Miami.