(CNN) -- Police were searching for a wildlife medical dart off the coast of New York on Friday after an unsuccessful attempt to euthanize a beached baby humpback whale Thursday night, according to East Hampton Village Police Chief Jerry Larsen.

The dart bounced off the whale and ricocheted into the Atlantic Ocean.

Larsen said Friday afternoon that the dart is encased in stainless steel but that it could pose a serious danger to swimmers in the months ahead.

"We're sending divers ... to retrieve the needle as soon as the surf dies down," Larsen said. Police also closed the area of beach, saying the dart might wash ashore.

The whale was found on Main Beach in East Hampton on Tuesday and was deemed too sick to save, according to Charles Bowman, president of the Long Island-based Riverhead Foundation for Marine Research and Preservation.

"The whale was debilitated," Bowman said. "It was a thin and a young juvenile still dependent on its mother and couldn't survive on its own."

By Friday, the whale was unable to free itself from the beach, and Bowman's foundation advised the National Oceanic and Atmospheric Administration that it was appropriate to euthanize the whale.

"It's heartbreaking for us. We're used to saving animals, getting them back in the ocean," Bowman said. "It's just one of these situations that there's just no chance for it, [and we are] trying to get people to recognize that."

A NOAA official shot and killed the whale Friday morning.