(CNN) -- A cruise ship passenger from Pennsylvania died Tuesday after being attacked by a shark while snorkeling with her family in the Bahamas, authorities said.
The passenger, a mother in her 50s who was onboard the Royal Caribbean ship, Harmony of the Seas, was attacked in Green Cay, off the coast of Nassau, according to Royal Bahamas Police Force Superintendent Chrislyn Skippings.
While the cruise ship was docked in Nassau, the family booked an excursion with a local tour company that took them to a popular snorkeling area, she said.
Family members then saw a shark attacking the woman and rushed to her aid. The mother had suffered bites to her "upper extremities," Skippings said.
Operators from the tour company and family members were able the pull the woman onto the boat and rushed to the nearest dock, where paramedics responded and reported no vital signs of life, Skippings said.
“Royal Caribbean is providing support and assistance to the guest’s loved ones during this difficult time,” a statement from the cruise line said. Harmony of the Seas is currently on a seven-night cruise after sailing from Port Canaveral, Florida, on Sunday.
The beach where the attack happened has been closed, authorities said, and the incident is under investigation.
Shark attacks remain extremely rare. The odds of getting fatally attacked by the creature remain less than 1 in 4 million, according to the International Shark Attack File.
Last year, there were 73 confirmed unprovoked shark attack cases worldwide, including 47 in the United States, which has the most documented unprovoked bites in the world, according to the Shark Attack File.
It's unclear why sharks bite, but experts say many attacks are “cases of mistaken identity,” occurring under conditions of poor water visibility, according to the Florida Museum of Natural History.
Many of the bites happen when humans are swimming in or near large schools of prey fish. Sharks may also bite because they feel threatened and are just trying to defend themselves.