Five people died off the coast of New Zealand this weekend after their boat capsized during a bird-watching excursion, according to multiple reports.
Police said the boat flipped due to a "collision," but did not elaborate further, the outlets reported.
According to Kaikōura Mayor Craig Mackle, the ocean was "perfect" and "flat" on the day of the incident, reported the NZ Herald.
Speaking with the Associated Press and RNZ, Mackle said that it is believed a whale surfaced from beneath the boat. Mackle went on to tell the AP that sperm and humpback whales were known to be in the area, which is a popular destination for whale-watching, according to the news agency.
The victims were members of the Nature Photography Society of New Zealand, according to the organization's vice president, Richard Hensby.
"The Nature Photography Society of New Zealand is saddened by the tragic loss at sea in Kaikōura during a trip by society members," Hensby wrote in a statement shared on social media, adding that until the investigation into "what caused the vessel to capsize" was complete, it would not be "appropriate for the Society to comment further."
"In the meantime, our thoughts are with the families of those members of the society who have lost their lives," the statement concluded.
Three of the five who lost their lives have been identified by loved ones as Susan Cade, Cathye Haddock and Peter Charles Hockley, according to The Guardian.
The survivors, who police said were all in stable condition, were transported to Kaikōura Health Centre, reported RNZ.
GCH Aviation Rescue pilot Andrew Humphries told 1 News that some of the survivors were "visibly shaken" and "startled" when he picked them up.
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"This is a tragic event that affects many lives, not least of all families and loved ones," Mackle said at a Saturday press conference, per RNZ. "Our heartfelt sorrow and condolences to you all."
An investigation is being conducted by Maritime New Zealand.