NANTUCKET, Mass. (WPRI) — New England Aquarium scientists spotted four orcas swimming together off the coast of Nantucket over the weekend.

The research team saw the pod of orcas swimming in formation while conducting an aerial survey on Sunday.

Orla O’Brien, an associate research scientist for New England Aquarium, said it’s unusual to see orcas, also known as killer whales, in New England waters. That’s because the species’ population in the western North Atlantic is very small.

“Seeing them swim in formation was just unreal,” O’Brien said.

O’Brien believes the orcas were two males and two females, though she acknowledged that has yet to be confirmed.

“I think seeing killer whales is particularly special for us because it unlocks that childhood part of you that wanted to be a marine biologist,” she said.

The four orcas were among nearly 150 whales and dolphins the research team spotted during their seven-hour flight, according to the aquarium.