WELLFLEET, Mass. (AP) — Animal rescuers were able to coax more than 100 dolphins away from shallow waters around Cape Cod over the weekend after about 125 of the Atlantic white-sided dolphins became stranded.

An estimated 13 dolphins died and one had to be euthanized, according to the International Fund for Animal Welfare, which helped lead the rescue attempt. The nonprofit said it was the largest mass-stranding it had dealt with on the Cape during its 26-year history in the area.

There’s no set reason for why these dolphins became stranded, rescuers said. Cape Cod is known as a global stranding hotspot due to the curvature of its shores and the fluctuation of tides.

Teams in Massachusetts found one group of 10 Atlantic white-sided dolphins swimming in a dangerously shallow area at dawn on Saturday and managed to herd them out into deeper water.

Scouts also found a second group of 25 dolphins swimming close to the shore near Eastham, the organization said. Teams worked to herd them away as the tide dropped throughout the morning.

Ten dolphins died during the stranding Friday at The Gut — or Great Island — in Wellfleet, at the Herring River. The Gut is the site of frequent strandings, which experts believe is due in part to its hook-like shape and extreme tidal fluctuations.

RELATED COVERAGE ThunderShirts, dance parties and anxiety meds can help ease dogs’ July Fourth dread Stingray that got pregnant despite no male companion has died, aquarium says Chinese woman facing charge of trying to smuggle turtles across Vermont lake to Canada

Misty Niemeyer, the organization’s stranding coordinator, said over the weekend that rescuers faced many challenges Friday, including difficult mud conditions and the dolphins being spread out over a large area.

“It was a 12-hour exhausting response in the unrelenting sun, but the team was able to overcome the various challenges and give the dolphins their best chance at survival,” Niemeyer said in a statement.

The team started out on foot, herding the creatures into deeper waters and then used three small boats equipped with underwater pingers, which make noise underwater, according to the organization.

Those helping with the rescue effort included more than 25 staff from the organization and 100 trained volunteers. The group also had the support of Whale and Dolphin Conservation, the Center for Coastal Studies, AmeriCorps of Cape Cod and the New England Aquarium.