EVERGLADES NATIONAL PARK, Fla. -- Wildlife workers in boats struggled unsuccessfully Wednesday to coax nearly four dozen pilot whales out of dangerous shallow waters in Florida's Everglades National Park, hoping to spare them the fate of 10 others that already had died.

The workers suspended their efforts after dark, but planned to return Thursday morning to try again, said Kim Amendola, spokeswoman for the National Oceanic and Atmospheric Administration, which is taking part in the effort.

Six of the whales were found dead, and four of the whales had to be euthanized Wednesday, said Blair Mase, coordinator for NOAA's marine mammal stranding network. At least three could be seen on the beach, out of the water.

The whales are stranded in a remote area near Highland Beach, the western boundary of Everglades National Park and about 20 miles east of where they normally live. It takes more than an hour to reach the spot from the nearest boat ramp and there is no cellphone service, complicating rescue efforts.

"We want to set the expectation low, because the challenges are very, very difficult," Mase said.

Park spokeswoman Linda Friar said rescuers were trying to surround the whales, which were in roughly 3 feet of salt water about 75 feet from shore, and herd them back to sea.

"They are not cooperating," Friar said.

Workers also tried to nudge the whales out to sea earlier in the day with no success.

The short-finned pilot whales typically live in very deep water. Even if rescuers were able to begin nudging the 41 remaining whales out to sea, Mase said they would encounter a series of sandbars and patches of shallow water along the way.

This particular whale species is also known for its close-knit social groups, meaning if one whale gets stuck or stays behind, the others are likely to stay behind or even beach themselves as well.

"It would be very difficult for the whales to navigate out on their own," Mase said.

Federal officials were notified about the whales Tuesday around 4 p.m. Because of the remote location, workers were unable to access the site before dark. They arrived Wednesday morning and discovered 45 whales still alive.

"There were some that were very compromised and in very poor condition," Mase said.

Four were euthanized with sedatives, and more could be put down Thursday if necessary, Mase said.