The National Oceanic and Atmospheric Administration said it is investigating why at least 10 small whales stranded themselves on a Maui beach Thursday morning.

Four of the beached whales were euthanized while the rest were refloated into deeper water and may have survived, NOAA Regional Marine Mammal Response Coordinator David Schofield said Thursday.

The dead whales were transported by cargo plane to Honolulu for postmortem exams to look for signs of disease or any other reason that would have led to the stranding.

The whales — possibly melon-headed whales or a similar small species — appeared on the beach in front of the Sugar Beach Resort early Thursday as others from the same pod swam about close to shore. One calf not part of the original 10 later washed up nearby, Schofield said.

>> Photo Gallery: 5 whales dead after mass stranding on Maui beach

Schofield said there was no obvious cause for the stranding, including no link to vessel activity. And while some stranding events are associated with sonar or other underwater noise, “We don’t necessarily believe this is related to that,” he said.

The rescue was supported by the U.S. Coast Guard, the state Division of Conservation and Resources Enforcement, Maui County, the Maui Police Department and scores of other volunteers.

Native Hawaiian practitioners also conducted protocol, including pule (prayer) before and after the whales were euthanized.

In a statement, NOAA said, “We have been working closely with Hawaiian cultural practitioners during this stranding response. We will continue to work with practitioners and other community members to the maximum extent possible, while we fulfill our mandate to conduct stranding response and post-mortem exams under the Marine Mammal Protection Act.”

Some Hawaiians expressed disappointment that NOAA put down the four small whales.

Native Hawaiian cultural practitioner Kealoha Pisciotta said the whales are the bodily form of the sea god Kanaloa, and she and about 10 other practitioners wanted to float the whales so they could swim away or die dignified deaths. She said NOAA officials wouldn’t let them do it.

“It’s really upsetting because why was that necessary? Why not give it a chance?” Pisciotta said. “There was a chance to help them, and we lost that.”

Vernon Kalanikau, another cultural practitioner from Kihei, agreed.

“For us Hawaiians, you gotta let the species die on its own. They could survive or die in a natural, normal way crossing over to the other side. If the human is intervening to kill the mammal, the mammal cannot experience a natural crossover,” he said.

Schofield said a NOAA veterinarian determined that the four whales were in grave condition and nothing more could be done to save them. The whales, he said, were first sedated and then humanely euthanized to relieve their suffering.

The remaining six whales showed signs that they might survive, so they were refloated back into the ocean. Two of the six ended up stranding themselves again and were eventually helped into deeper water.

The University of Hawaii Stranding Lab will conduct postmortem exams, the results of which could take months to complete, Schofield said.

The effort is part of the Pacific Islands Region Marine Mammal Response Network, a group of government agencies and nongovernment organizations that respond to marine mammal strandings in the main Hawaiian Islands, Northwestern Hawaiian Islands, Guam, American Samoa and the Northern Mariana Islands. Twenty to 30 cetacean strandings are reported in the region in an average year.

Schofield said the Hawaiian Islands usually experience only strandings of single animals, but mass strandings do happen on occasion.

For example, five pilot whales died on Kauai’s Kalapaki Beach in October 2017 after 17 pilot whales stranded there. The rest returned to the open ocean. The cause is unknown.

In 2004 between 150 and 200 melon-headed whales occupied the shallow waters of Hanalei Bay for more than 28 hours before returning to deeper water with human help. Speculation at the time was that underwater noise had driven them to land.

Star-Advertiser staff writer Leila Fujimori contributed to this story.